SDL Authoring Bridge in oXygen 20.1: The creation of the account failed / Unable to reach the Repository

Hi. We've set up a dev server and a QA server in our Tridion Docs 14SP1 deployment environment. I'm able to connect the Authoring Bridge to our pre-production learning environment and our dev environment. (Both pictured below.) However, we are having problems connecting to our QA environment, which should be set up identically to the dev environment. I don't understand how to implement the recommendation in the dialog or what it's actually asking us to do. Google hasn't come back with much relevant/useful stuff.

What can I do to resolve this and other client connections (such as Publication Manager)? Thank you!