Adobe Digital Editions 4.5

Hello,

I downloaded Adobe Digital Editions 4.5 to my MacBook Pro (2019) (most recent Big Sur OS) successfully under Applications.  And the Help field shows that this computer is authorized.  And then Itried to download a textbook whose publisher setup the download for this software.  But I keep getting a license error -- that says "Unable to Download -- Error getting License. License Server Communication Problem:
E_ACT_NOT_READY"

I tried another MacBook Pro from work -- same message.

I tried de-authorizing the computer but the software doesn't allow me to do that.

I was however able to download this book to my iphone and an early generation ipad mini using this software.

Tech support at the publisher doesn't understand the problem.  Adobe tech support said they don't support this computer.

Could you suggest anything that might help?

Thank you.

John