If you've got a question about syncing your music offline, we have a couple FAQs here:
If tracks or playlists aren't fully syncing, check:
Yes. You can save playlists for offline use on up to 3 devices. For example, you could use offline mode on your computer, tablet, and mobile phone at the same time. If you attempt to use offline mode on more than three devices, the oldest registered device won't work offline.
With a Spotify Premium subscription, you can sync for offline use 3,333 tracks from the Spotify catalogue on each device (phone, tablet, computer, etc.). If you're syncing your local files, there is no limit.
Have another question? Post it here and a member of the Community can help!