@Salamftw best reach out to email@example.com regarding this issue. I am sure we can help in 99% of cases the email address turned out to be wrong after all but we will be able to determine that over at support.
Unfortunately, Big Sur gives us quite some challenges we have to evaluate first. Apple decided to push this update on developers and not only CU has problems adapting to it. Our game Engine (Unity) for example also hasn´t been able to get proper updates before Big Surs launch.
We are doing our best to assess the situation and find solutions but we also will have to wait for the "big guys" to get their act together to provide us with the needed support here.
@laynevanb Unfortunately, I can't post pictures here - so I will have to try to describe it. I'm describing the screens from the Steam app, but the Android and IOS apps, and the browser version should be similar.
In the app, on the opening screen, click your avatar. In the new window, click "Friends". This will bring you to the next screen with a "Filter" box and "Friendlist" / "Blocked" headings. At the bottom there should be a button labeled "Find Friends" - click this.
A new pop-up window should appear with "Add a Friend" at the top. Type your friend's user name (exactly as they spell it in Catan Universe) into the search box. Their name should pop up in the list below the search box. Click the name, then the box at the bottom "Send Friend Request" should become active - click it and it will send the request.
If the person accepts, they will be added to your friend list. You can use your friend list to invite them to custom matches in Catan Universe.