Spotify/Plex Sync

GOAL : Me (and my family) place music in separate Spotify playlists. 1). Songs in those playlists are downloaded to my server and then 2). are synced to plexamp (paid). Finally I would 3). expand this to some way to find New Music in a playlist (which would also sync). I can do 1). (Spotify-->Server) easily on a few apps (Downtify, Spotify to Plex, Lidarr). But re-syncing them to identical playlists escapes me. Aurral has a neat discovery system but no spotify sync (yet). Any ideas? All I got is running mul