Any way to import playlists?

Is it possible to do this with a local NAS running Plex or must it be a local Plex Media Server?

I have been trying to send m3u playlists to my Synology drive through Postman for a few days now, but I can’t seem to figure out what’s going wrong in the process. I get STATUS 200 OK, but no playlist ever populates on the server. I get synced m3u files, but that’s it.