I once had linked two hotmail accounts in my Microsoft Outlook Mail app. There wasn’t a problem until one day I forgot the password and the other details of one of the hotmail account which failed me to recover the password.
When I’ve updated to Windows 10 Creators Update, strange messages started to keep poping up as shown below.
“We need to fix your Microsoft account before you can use Shared Experience. Select this message to open Settings and fix things.”

Whenever I clicked on the message it always asked me to enter the password of the Microsoft account which really don’t recall the details.
I also checked the Shared experiences in the settings and have it turned off but still continuously get the above message.
The Solution
This has been a long issue which I didn’t bother but this time I really find time to have it solved.
Since I already have the Shared experiences turned off in the settings, there must be some other setting or configuration left why a certain email account was kept getting asked to provide for a password.
So I looked over Settings > Accounts > Email and app accounts and found that there indeed was the email address that causes never ending popup message as shown below.

So, I just removed that certain email address and that resolved the issue.