In a civil suit, the burden of proof is 50.01%.
The jury didn't find that he put his dick in her, as she claimed.
Somehow the judge found that, despite the jury's verdict that he didn't rape her, her claim that he raped her was "substantially true".
Even if it were someone else (not Trump), I'd have a hard time believing her because of her decades of comments about how good rape and other sexual abuse is.