How do I sync my music library from my iPhone to my MacBook Air? I just purchased a MacBook Air and I'm trying to sync my music library from my iPhone 6 to the new Macbook and only music purchased from the iTunes Store shows up on the MacBook although I have lots of other albums on my phone?
iTunes does not sync non-purchased music (or movies or tv shows) from a device back to the computer. You will need third-party software on the computer, such as iExplorer, to complete this.

(I swear there was another question like this that has been answered before, but I couldn't find it.)