I have not seen this particular problem here (though I may have missed it). If anyone - especially somone from Adobe or 3M cloudLibrary - knows how to deal with this, I am all eyes. Please bear with me while I recount the story.
I bought a Kobo many years ago and installed ADE. Borrowed many books and read them successfully. The ADE upgraded and the autohorisation somehow stopped getting through to Kobo. The workaround that many suggested, and that works, is to downgrade ADE to version 3.0, which I did. All was well for a few years, until about a month ago. One of my libraries has a QuickRead feature (borrow a book for a week) that requires cloudLibrary. I installed it, borrowed my first book, renewed it (it was 500 pages long, a bit much for a week) and read it. This was 2 weeks ago. Last week I borrowed a book and it would not open in Kobo (authorisation). Of course, as many noted, I could not deauthorise ADE, so I had to edit the registry, remove the appropriate entry, reinstall ADE - and it worked. Finished it and borrowed a QuickRead book yeasterday. CL gives me the dreaded E_ACT_NOT_READY message. I uninstalled it many times, including a very clean install - removed all mentions of Biblotec on the computer, including the registry. Still no go. Thinking ADE is mulfunctioning again, I borrowed a book to put on the Kobo and it worked like a charm.
The problem, therefore, seems to be that CL cannot find the correct authorisation. I have no idea how these things are interrelated and if perhaps removing both ADE and CL and cleanly and reisntalling CL first and ADE second might help.
The MAIN problem is that neither ADE nor 3M cloudLibrary (Biblioteca) provide any support and that no documentation with enough detail is available.
I am pretty sure others have similar problems; some have been discussed here many times.
Thanks for your patience and possible suggestions.