Hello @PAUL FRANCISCHETTI,
Thank you for posting your query on Microsoft Q&A.
Based on your issue description, I understand that you are setting up a new windows computer and you are on the page to add your Microsoft account; yet when you enter the account name a message tells you the account doesn't exist.
1.Could you please confirm if you are following the below steps to add your Microsoft account to your new device.
2.In your device, Go to Settings -> Accounts -> Access Work or School -> Click Connect and Add your Microsoft Account.
Below is the Screenshot for your reference.
3.Please double-check the Microsoft account email that you are entering is correct or not. Please make sure there are no typos, and it's the right account you intend to use (e.g., Outlook, Hotmail, Live).
4.Please try signing in to your Microsoft account using a browser (https://account.microsoft.com/) to see if that Microsoft account exists and you are able to log in. If you can't sign in online, the issue could be with the account itself.
I hope this above information provided is helpful. Please feel free to reach out if you have any further questions.
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