Acrobat vs Digital Editors

[vc2000]

I purchased an e-book, the download had an "acsm" extension. This download prompted Digital Editors to open it. The file works fine, but I do not like the Digital Editors software, I prefer Acrobat. Since the file shows up in the folder as a PDF, I tried to open it with Acrobat DC. But I get an error message saying that the "Plug in required is unavailable". Is there a way to open this file in Adobe Acrobat? 

[sergepaulus]

eBooks are in ePub format, which Acrobat can't read. I'll be glad to know alternatives to Adobe Digital Editions, as I can't run it on my computer!