Ok, thanks folks. Since I got it through CW (?) it's actually linked to my XLN account, along with AD2. I have the serial number, but XLN's site wanted an activation code and the serial didn't work (as the activation code).
As far as entering the serial in the plugin interface itself, I should have mentioned that it was actually a weird Windows 10 error (I think), something about administrator privileges not being able to write or apply or copy the license file or something. It sounded like the plug wanted to authorize, but W10 didn't let it (?). My W10 User Account is Local/Administrator, but I couldn't get around the error.
So there's that, if any W10 gurus have any idea.
Thanks again, appreciate it. I have all the usual full-version plugs (GR 5, Ampl. 4, etc.), and they're awesome, but I do think Revalver brings a different sound to the table, so I don't want to lose it.