Cannot authorize computer

The solution to this is to "Erase Authorization" and then try authorizing it. This worked for me.

You are trying to authorize a computer that you have previously activated (or that ADE thinks you have previously activated) anonymously.

You can only upgrade using a brand spanking new AdobeID, that you haven't used before, anyplace.  Which is what the error message is saying.

If you care about keeping access to the books on currently on your computer, then those are the rules you need to follow.

If you don't care about the books currently on your comptuer, then you deactivate (Ctrl-Shift-D) and then when you relaunch ADE it will ask for an AdobeID, and you can enter whatever one you want.