RPDB-Folders monitors media folders and adds images with ratings (poster.jpg / background.jpg) from the RPDB API, like below:
Once you've enabled it in your account, launch the app via your dashboard.
You'll need to subscribe to RPBD via Patreon in order to get an API key.
Once you've entered your API key into the UI, use the "Add Movie Folder" or "Add Series Folder" button to add a folder.
Instead of browsing for a folder, click in the text box illustrated below..
Manually type in the path to your movie/series folder (starting with
/media/), and click "Save Location":