Spotify wont sync local songs to phone

[GrandMasterLP]

I had a playlist synced before, had all my local files. I tried to add a song and it messed up everything. I undownloaded then redownloaded the playlist and now I get the "you must own the song" error. I did all that sync offline on phone and computer trouble shooting. I'm not sure what the promblem is since I already had it working before. Pretty frustrating. Spotify please make a local file sync that is user friendly.