Why does my apple music say icloud music library cannot be turned on because it’s associated with another apple id

I don't really understand these messages.Yes,I get it that DRM (digital rights management) has to be adhered to but these messages are confusing because once you try and change an Apple ID on a device that has had an Apple ID before, then you are locked out of using iTunes for 90 days.

The device software should tell you this with a step by step explanation of what to do and how.