The 30-year-old Folau was after $14 million in compensation for wrongful termination after RA sacked him for a code of conduct breach when he said on Instagram earlier this year "hell awaits" gay people.
RA was determined to hold its ground as mediation ordered by the Federal Circuit Court began this week and a marathon 12-hour session on Monday failed to yield a result as both sides remained at loggerheads.
However, on Wednesday afternoon, Folau and RA released a joint statement saying they had reached an agreement, settling for a confidential amount.
The Daily Telegraph reports that Folau received $8 million in the payout.
Castle went on Twitter to say the settlement number was confidential.
"Folau settlement numbers are confidential but numbers being speculated are wildly inaccurate," Castle said.
Former Wallaby and writer Peter FitzSimons guessed a much lower figure.
"I have no inside knowledge of the terms, not even a hint, but my bet is it will be about $200,000 to $300,000," he said in a column for the Sydney Morning Herald.
Yesterday's statement said Folau "does not condone discrimination of any kind" and also reinforced RA's position that it does not agree with his views because the governing body preaches inclusiveness within the sport.
Both parties apologised for any hurt the damaging saga has caused.
"Rugby Australia, NSW Rugby and Israel Folau have today settled their legal dispute following the dismissal of Israel Folau after he posted a religious message on social media," the statement read.
"The social media post reflected Mr Folau's genuinely held religious beliefs, and Mr Folau did not intend to harm or offend any person when he uploaded the social media post.
"Mr Folau wants all Australians to know that he does not condone discrimination of any kind against any person on the grounds of their sexuality and that he shares Rugby Australia's commitment to inclusiveness and diversity.
"Rugby Australia and NSW Rugby do not in any way agree with the content of the social media post. Inclusiveness is one of rugby's core values and it welcomes all people to the game, including all members of the LGBTI community.
"While it was not Rugby Australia's intention, Rugby Australia acknowledges and apologises for any hurt or harm caused to the Folaus. Similarly, Mr Folau did not intend to hurt or harm the game of rugby and acknowledges and apologises for any hurt or harm caused.
"Rugby Australia and Mr Folau wish each other well for the future. The Parties do not intend to comment further on the terms of their settlement as it is confidential."
Last week Folau lodged an updated statement of claim in the Federal Circuit Court, upping his pursuit of damages from $10 million to $14 million.
Folau justified the $4 million increase in part by saying he was in line to captain the Wallabies, which would have boosted his income. But that assertion was rubbished by former teammate David Pocock.
"I think Michael Hooper has been doing a great job and he's contracted to the next World Cup so I'm not sure where Izzy's getting that from," Pocock said on Fox Sports News last week.
"My view has been that sport is at its best when it's challenging society to be more inclusive.
"I think we can play such an important role in trying to instil values of fairness and inclusivity into kids coming through.
"I found it incredibly disappointing the way he's used his platform around this."
In his updated statement, which some speculated was a legal ploy to pressure RA into settling for more money, Folau said his contract termination will cost him $4.2 million from 2019-2022, as well as $300,000 in match payments from 2019-2021 and an additional $150,000 in match payments in 2022.
He also claimed he stood to make up to $1.5 million a season for one or two years with Rugby Australia and a Super Rugby club after 2022.
Folau suggested he would have earned up to $1.5 million a year for two-to-three years had he chosen to play overseas after his international career ended.
Estimates provided over lost sponsorship dollars and the missed revenue that comes with competing at World Cups and possibly captaining the national team were also used to justify the controversial star's $14 million demand.
How the Folau saga unfolded
11 April 2019
Folau weighs in on the gender birth certificate debate in Australia, saying again homosexuals will go to hell.
This follows after Tasmania became the first Australian jurisdiction to make gender an option on birth certificates. After the announcement, Folau took to Twitter to tell people to "turn away" from their evil ways after the announcement.
A short while later, Folau warned sinners would be going to hell unless they repented with this Instagram post:
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Rugby Australia later confirmed it was investigating the comments, saying in a statement the posts were "unacceptable" and "disrespectful".
12 April 2019
Wallabies sponsor Qantas join the growing chorus of outrage at Folau's posts, saying the comments "clearly don't reflect the spirit of inclusion and diversity that we support".
15 April 2019
Wallabies coach Michael Cheika says he will not select Folau for the Wallabies after his "disrespectful" social media posts attacking gay people.
17 April 2019
It is revealed that Folau plans to contest any action taken by Rugby Australia and that the governing body could find itself in a precarious position, with major sponsors closely monitoring the ongoing saga.
19 April 2019
The panel for Folau's code of conduct hearing is confirmed, with John West QC the chairMAN. RA's Kate Eastman SC and Rugby Union Players' Association representative John Boultbee AM are announced as the other panellists as Folau fights to save his career.
3 May 2019
Video emerges of Folau fighting back tears while delivering a sermon at his church on Easter Sunday.
4 May 2019
Ian Roberts, the first Australian NRL player to publicly come out as gay, issues an emotional message to Folau warning that "literally kids in the suburbs are killing themselves" over remarks like Folau's.
7 May 2019
Folau is found guilty of high-level breach of Rugby Australia's code of conduct after a four-day hearing in Sydney.
8 May 2019
Folau says he's "at peace" with the verdict, according to outspoken Australian radio host and former Wallabies coach Alan Jones.
9 May 2019
Folau is dumped as brand ambassador by sportswear company ASICS over his homophobic comments.
10 May 2019
It is revealed that Folau turned down an offer of $1 million to walk away from his contract and that he refused to remove the social media posts when offered a lifeline by RA.
13 May 2019
Folau's relationship with long-time manager Isaac Moses is reportedly on the rocks, as the 30-year-old fullback "all but turned his back" on the man who has been in his corner since he was 14.
17 May 2019
Australian media report Folau will take RA to the Supreme Court if his $4 million contract is terminated.
17 May 2019
Folau's contract is terminated by RA, with chief executive Raelene Castle saying the outcome is a "painful situation for the game".
6 June 2019
Folau launches legal proceedings with the Fair Work Commission against Rugby Australia and the Waratahs. It is later reported that he is suing them for $10 million for "unfair dismissal".
27 November 2019
Folau lodges an updated statement of claim in the Federal Court, now demanding $14 million in damages from Rugby Australia, claiming he could have been captain of the Wallabies.
2 December 2019
Folau starts his legal battle against Rugby Australia with a mediation meeting at the Federal Court in Melbourne.
4 December 2019
Folau and Rugby Australia announce that they have reached a settlement.