Once you clicked Play on the original website, Acrophobia would have automatically launched. However, Bezerk Revived doesn't support this. In order to play Acrophobia, go to where you extracted the files for the version you want to play, and then double-click on "Acrophobia.exe".
I may or may not support this "auto-play" feature in the future. It depends on how I could potentially get it working, since modern browsers no longer can use the method that Acrophobia used to open itself.
Bezerk Revived is not associated or affiliated with Sierra.