I kinda get how you might do it with a desktop running roon, but how do you do it with ROXK?
Importing playlists into a running Roon server is not easily done.
However, if your playlists is placed in the same storage space as your media files they would be imported simultaneously as the media import, unless you chose not to.
Look in Storage-Edit for the checkboxes.
Unless you’re talking about playlists from streaming services? In that case Soundiiz is your buddy!
It does not matter where your Roon Server is running, you still control it from your choice of Remote.