I'm wondering how this is going to go for Libby/OverDrive stuff. I only used ADE in wine a while back to set up DeDRM in Linux when I checked out a book that didn't sync on my Kobo, doing the full “Windows version of Python” dance to get the credentials in the format DeDRM uses.
I've tried migrating just now and got the USER_DOES_NOT_EXIST error. Apparently
others are having the same problem. I might try emailing them later on.
Here's
OverDrive's help page about the ByteBooks ID.