Getting Adobe Error on Download from Public Library to Adobe Digital Editions

I had an old Sony reader and replaced it Kobo, it’s been working fine however I cannot seem to download books from the public library.

I am able to successfully download a books from Kobo site to Adobe Digital Editions and drag it to my reader. However, I cannot download from my public library to Adobe Digital Editions I get the following error ‘ Adobe reader cannot open book title.acsm because it is not a supported file type or because the file has been damaged’ I have uninstalled/installed Adobe Digital Editions 4.0 still cannot download. Any ideas ??