Q: error this device is already associated with an apple id

ok so I purchased a used ipod 5th generation. It was wiped clean when I got it. I set it up with my apple id. But it doesn't put my music library on the device when I try syncing it. It put my icloud music on it. Then when I try to play that music I get the box that says this device is already associated with an apple id. Also when I go into manage devices its not showing up there. It does show up in my iTunes though when I connect it. What could be causing this? Please help!