ADE 4.5.4 Won't Install ~ Unable to Open .acsm file & download .epub

I am trying to download a book that I purchased. I click on the .acsm file and it asks to reinstall Adobe Digital Editions each time.

Windows 10 laptop.

I click on an .acsm file, which the file properties show is already associated with ADE 4.5.4 and it says: "Do you want to allow this app to make changes to your device? I click yes, it sends me back through the set up process."

Doesn't download the ePub book.

I click on the .acsm file again. It runs me through the entire process all over again... no success.

Can anyone shed any light on this problem?