Hello, happy to help here.
Just follow these:
Go to https://signup.live.com and choose Create a new account.
Enter your desired email and complete the form with password, country, and birthdate.
Sign in at https://outlook.live.com with this new account only.
Avoid signing in with any other Microsoft account during setup.
You can set it as default in Windows Mail if needed.
Just let me know if you have further questions, stay safe!