Configuring preferences and options in Outlook.com
I'm afraid I can't help. But I also have the same problem.
I changed a password on Gmail, then I started getting messages to change the settings in Outlook. However, I get the same error message when I try to access the Sync Mail and other settings.
It's great that Outlook has automatically identified the problem and is giving me instructions about how to resolve it.
But it's frustrating that I can't carry out the instructions!
Hopefully, this will get sorted soon.