Adobe Digital Editions Trouble Accessing Books on New Computer

I have had the Adobe Digital Editions reader installed on a computer since this summer, when I needed it to receive an e-book sent to me by a publisher. Recently, I accessed a book through a university library through the ADE reader. There were some initial problems downloading the book to the reader, but it finally downloaded.  When it did, I noticed that the earlier book was labelled "Missing." 

This week, I have a new computer and am trying to access both books. Since ADE reader was not installed on my computer when I bought it, I went to the site and downloaded and installed the software. I also accessed my account, through which I purchase other Adobe products. ADE reader was not there--maybe because it is freely available and not a subscription?

Anyway, when I returned to the reader itself, neither of the books was there. Shouldn't those books be accessible to me from the Cloud somewhere. I don't recall having to register it in anyway and I have no record of User Name or Password that would go to an account. How do I access these books from ADE reader on my new computer.  Do I have to go back to the publisher and university library and access them again. Particularly concerned about the latter, as I have e-annotated the book heavily and do not want to download a new version that would erase or override the one with the notes. Please advise. OS = Windows 10