Adobe Digital Editions version 3.0 mac os download issue

I am trying to download Adobe Digital Editions version 3.0 on my mac device. I am getting an error saying "Adobe Digital Editions 3.0 needs to be updated. The developer of this app needs to update it to work with this version of macOS. Contact the developer for more information. "

I need the Adobe Digital Editions to access my textbook for an online class.