I'm having the same problem. I verified my connection to the internet by logging into my Adobe account, and even went through the Adobe troubleshooting procedures following the link there to the page that says "Welcome to Adobe Digital Editions", which Adobe says means I'm reaching the authorization server. But either that's wrong or there is a bug in the Adobe Digital editions. One says I'm not connecting to the authorization server and one says I am. The result is the same. I can't authorize my computer to save the book I downloaded.
So how about it Adobe? What gives? Should we give up on ADE?
Restart your machine and try again. !!
Hope this help.
I am having the same problem and restarting my machine has not solved it. do you have any other advice?