can't download books

I have deleted and reinstalled Digital Editions as well as Adobe Reader, also confirmed I have an ADE ID....all this done today, them tried to download a free book to see if it would work, and received message : could not open URL Link (3) acsm because it is not a supported file type. What step am I missing here...I can receive books from Kobo, so not sure what is happening.....thanks Barb