A Microsoft file hosting and synchronization service.
I had to go out on an errand this morning, so I've now come back to retry - I started the process again, using my OneDrive username and the App Password I generated earlier.
And now that I try again in exactly the same way I was doing before... I now get this error:
It would seem to me that this Windows 10 error message is likely equivalent to the slightly more user friendly Windows 11 you've shown there.
I've confirmed I am using the proper addess by reloading Excel and checking I can successfully open one of those recent files in that shared folder and that the shortcut URL hasn't changed - all fine, no change there.
I can only assume that Microsoft is changing things in the backend, as I can think of no other reason why trying to access it the same way and getting a different result!?
(Also, please MS, re this interface, when replying in-thread, why would you make it so that sometimes when hitting the up arrow, as you might reasonably do while editng text, you would send me to the top of the page - my scroll wheel is ageing fast! 😆)