How do I authorize or re-authorize my computer?

ADE won't allow me to transfer library books from my laptop to my Kobo saying that authorization is needed.  The eBook vendor field defaults to "Adobe ID" and there are no other options available.  I've entered my email address in the Adobe ID field and my newly created password.  The resulting error message reads "The vendor account you entered is not associated with the item you are trying to open. Try again."  The Adobe website seems to recognize me so I don't know why I can't get authorization.  I've uninstalled ADE 4.5 and tried version 3 instead but it's still a problem.  I've been downloading to my Kobo e Reader for years so why can't I do it now?  I'm using Windows 8.  Is there anyone out there that can help me?