Error--E_AUTH_BAD_DEVICE_KEY_OR_PKCS12--What is this?

I tried to restore a text book for school that I had to purchase outside of iTunes.  My iPad was damaged and was replaced under Apple Care.  I backed up my iPad including the text book to iCloud.  When I restored everything to the new iPad, this book did not restore.  I checked my ADOBE ID and have tried to work with the text book publisher.  I continue to get this error.

What does this error mean?

TD