Apple Music playlist on iPhone6 doesn't match same playlist on iMac.

I have had Apple Music for a year. Due to the fact that I drive a lot in areas where there is no available internet connection, I try to download songs I want on my iPhone to my Mac at home and sync the playlists so I mostly have the downloaded music on my phone. However, this doesn't work very well. I have the playlists but the songs aren't syncing correctly. (I'm missing a lot.) Also, I can't seem to get rid of playlists that I do not want on my phone.

I have been looking through the communities to see if anyone else has had this problem & I've seen a few posts but no solutions that work.

I have iCloud music turned on.