I must be blind but I can't find a user guide anywhere and I just want to know how to use this with downloads from services like Rapidgator or Nitroflare. Thanks!

Hello,

Unfortunately, there is no user guide available.

It seems that these services are not supported. Both of them are in the "Skip domains" list in FDM's settings by default. However, it's possible that things could be changed since the last time we checked it.

So, you may try the following steps:

1. Install FDM extension into your web browser (for this, go to FDM settings, Browser Integration section).
2. Remove these services from "Skip domains" list (the same Browser Integration section in settings).
3. I recommend to restart your web browser after this (just in case).
4. Try to download from these services using your browser. FDM should catch the download from your browser then.