Digital Editions errors - unable to open books or erase authorization

I switched Macs 5 days ago and have been unable to use ADE since. I keep getting errors when I try to open or add books (see pictures). I am unable to erase the authorization from my computer; I keep getting an error message telling me to "try again after some time." I tried uninstalling and re-installing the program and it's still not working. I contacted customer support and was told to post in the forum. I'm using the most recent edition of ADE and the Big Sur OS, same as I was on my previous Mac. I have a Kobo e-reader, which I had no trouble loading books onto until 5 days ago.