I can't sync my music to my new iPhone
Go to Settings > Music. Is "Show Apple Music" switched to "on?" 

You cannot have Apple Music enabled and sync your music library. It will only make those songs in your library available via the cloud.

You must choose, for your device, if you want to have Apple Music (which has a paid subscription fee of $9.99 after a trial period) -or- sync your music library. 

You can, however, download songs individually onto your device for offline use.