Music on MacBook Air iOS Sonoma 14.5 not syncing with iPhone 14 iOS 18.0.1

After numerous updates to apps and iOS versions, I am still unable to sync my music library to my iPhone. I do not get an error message during the sync, but when I try to play music on my phone while offline I am told I need to be connected to wifi or use mobile data. When I sync, selecting specific albums/songs/playlists etc am I not downloading these selected items to my phone? I have been through the process of deselecting and deselecting what I wish to have on my phone many times but it still won’t work (ie zeroing the sync and redoing the whole process). I do not have ready internet or phone access so “call Apple” won’t work, nor will “reinstall Music”. Why can this issue not be fixed? It seems to have been around for many years and many updates to all the associated bits?!