Solved! Musescore 4 doesn't open files that have been stored online

Problem solved itself somehow!

I have stored a lot of files online.
Now, when I try to open either of those scores Musescore 4 doesn't open the files and tells me I was not logged in. But that's not true.
The musescore website lets me watch and play my scores and is telling me I was good to go back to the desktop app and edit my scores. But back there I am told I should check my internet connecting or try again later.
The internet connection is fine and waiting for some time didn't change anything .
I also tried reopening Musescore and restarting the computer – no success.
I am on an Intel iMac with OS Sonoma 14.1, Musescore 4 is up to date.