ADE 4.5.3 start up opens but no book downloaded

I have Windows 10 and just changed from ADE 3.0 to 4.5.3.  Have not had any problem downloading library books to ADE and then to my NOOK until now.  When I try to download a new  EPUB book, clicking the download button brings up the ADE startup screen with the question..do you want this program to make changes to your computer...clicking yes, the app downloads again and then opens showing only the library books I had previously borrowed and am reading. The new book will not download.  If I click no, the message "installer requires administrative access, aborting".

Have removed and reinstalled ADE several times.   My desktop is registered and I have erased and reauthorized it several times too.  I even tried going back to ADE 3.0 but that didn't work either. 

Please help! 

Carolyn