I'm not 100% sure, but the GLO may have two registrations, one for Kobo books specifically and one for general Abobe ID books.
When the GLO is connected to the computer with USB, it should show up in the left panel of ADE. Does it do this?
If so, try menu/Help/Authorize Device (Library/Authorize Device on the older more reliable ADE v1.7.2).
If the GLO is properly registered to your Adobe ID but ADE won't recognize the Glo at all,
try copying books from the computer to the Glo as a mounted drive, using your file manager (Windows Explorer, Mac Finder).