Capture One offers a 30-days free trial of the software that can be downloaded here. Instructions on how to activate it are provided in this article.
It is not possible to reset the trial once it has expired.
Capture One trial (any version) can be used one time per dot-release only.
If your trial has ended but you are not yet done with testing the software, consider obtaining a monthly subscription that you can cancel in a month or two, depending on your needs, or wait until the next dot-release comes out.