Hi,
Try activating a standard local account and see if the problem persists.
Go to Start menu > Settings > Accounts > Other users > Add account > select the option that says "I don't have this person's sign-in information" > Add a user without a Microsoft account.
Then access the new local account and try launching the Microsoft Store to see if it works.
Which version of Windows are you using, Windows 10/11 25h2 or 24h2?
Thanks