The "Agreement" is binding between both parties. The WT likely agree to pay more than expected, and pay for all here legal expenses. When an individual, or small company, goes after someone that big, they can just wear you down and make it run out for years. I'm sure she and her lawyers were acutely aware of this, and made her an offer to end it. I'm sure her lawyers were getting buried in costs and had to asses the risks in court or wait for years to see if they ever get paid.
The agreement probably has a provision that if she ever discloses ANYTHING about the matters/case it may void the binding agreement and she would have to forfeit any financial consideration (payoff money). It was done very intentionally to prevent her from being a witness is any other case they are worried about.
I think it's safe to say that she did not request the non-disclosure clause. The public can say that the WT paid her off - to keep her mount shut - and cannot ever testify. Rock and a hard place. She can be called to testify or held in contempt. But if she does, the binding agreement is separate. She would have to give the money back and left with HUGE legal bills to pay on her own.