Need to authorize my computer for ADE (3.0) when I'm not sure of the reauthorization ID or password

How do I find out what the ID and password is to successfully reauthorize my computer for ADE 3.0?

I have an older, Nook Glowlight+ E-reader version and I can't read checked out books from my local library using Overdrive.  The ADE community has suggested I delete ADE 4.X version, install ADE 3.0.  Deauthorize my computer.  Get out of ADE.  Get back into ADE and reauthorize my computer for ADE 3.0.

I've done everything except for reauthorizing my computer for ADE 3.0 because (it's obvious) my user ID and password to do that is different than the Adobe User ID and password to access this community forum.