It was a defamation case in which the courts determined that Trump made false statements by denying the allegations because he most likely did sexually assault E. Jean Carroll.
No criminal case was brought because it's beyond the statute of limitations, and since the legal bar in a criminal case is higher I don't think any prosecutor would bring those charges even if statute of limitations wasn't an issue.
At the time when Carroll alleges Trump raped her, the statute of limitations for rape in the state of New York was five years.