You can find the answers to many questions here, it’s very likely someone before experienced the same problem as you do. Otherwise you can also submit an issue ticket and wait for our help.
If plug-in you've just installed doesn't show up on plug-in list in Reaper, please walk through following steps:
First of all make sure all Software Requirements are met by your setup.
Additionally if you're Windows user:
Try out the solution described in this entry at our FAQ. It's possible that some system runtime libraries required by plug-in are missing. This concerns especially relatively fresh Windows installations.
Still no success? Try doing full plug-in rescan in Reaper:
Use the search or contact our staff:Submit a ticket