"Network Connection Lost" when trying to download audiobooks - Catalina

I am running Catalina 10.15.7.

Attempting to download some audiobooks I'd purchased on my iPhone to my iMac. Every time I try to download a purchased book I get a "Network Connection Lost" error. I've checked to make sure the Audiobook/Books server is active (it is). I also definitely have internet connection. I've double-checked to make sure I am logged in with the correct Apple ID. I've re-started my computer twice. Still... cannot download purchases using the Books desktop app on Catalina.

I wanted to then just transfer purchases from my iPhone with my iPhone connected to my iMac, but apparently that doesn't appear to be an option anymore? All I get is the option to sync my books on my machine with my iPhone.

Appreciate any assistance and suggestions on what I may be missing. Thank you.