Thank you for your detailed post!
For the error you received when logging into your AzureAD account, you can try resetting your password from within AzureAD and logging in again. This way you can make sure that you're entering the correct password.
If you're still experiencing issues logging into the Microsoft Store, I'd recommend reaching out to our MS Store experts via their support page.
If you have any other questions, please let me know.
Thank you for your time and patience throughout this issue.
Please remember to "Accept Answer" if any answer/reply helped, so that others in the community facing similar issues can easily find the solution.