Seems there is a lot of us getting this problem
My internet connection passes through some firewalls/filters. When I managed to direct the internet connection around these ,
I was able to download e-books again. Everything is OK now.
I am having the same problem but only one of my two computers. Everything works fine on the other. I've reinstalled the application. Also tried to deactivate but it won't allow me to.
Okay, I got help from my library. Need to delete the activation.dat file in the Library folder. It was a hidden file on my computer so you may need to do a search. After deleting, restart ADE and reauthorize.
Thanks to the Vancouver Public Library tech support.