Using Outlook for Android for personal email and calendar management
If a message pops-up that there is already an existing account that is linked then you might have previously done this and have forgotten it.
In this case, Microsoft has no access or no visibility to PSN accounts to see this and therefore you can reach out to the PlayStation/Sony support to check this from their end.
https://www.playstation.com/en-us/support/
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information.