Apps for moving music from one phone to another?

Level of difficulty: can’t just swap the SD card.

I went from a One Touch on T-Mobile to a Moto X on AT&T. The X has built in memory so can’t transfer the SD card. Different SIMs as well. I tried using the Moto transfer app but it fails around 8% into the media portion. I tried to use the AT&T app but it’s under revision so that’s out. The laptop is out of commission for now so that’s out.

I’ve been able to swap/backup/etc all my apps, contacts, bookmarks and such. What I need help with is getting all my music files transferred. I used the file manager to try to “share” the files to Drive, but the share icon is shaded. I attempted to connect them via WiFi but either that won’t work or I don’t know how to do it.

So. Are there any apps, free, that will let me get these songs from one phone to the other? I thought of Dropbox but assume I’ll get the same result as Drive.

Thanks