Using New Outlook on Windows for personal email, calendar, and contact management
Hi. I'm Brian and I'll try to help.
Since this forum is dedicated to using new Outlook for Windows with a personal (not work or institutional) account, I'll assume that's what you're using.
When you created the account, did you allow new Outlook to configure it automatically? Have you tried removing and re-adding it? Can you log into https://outlook.live.com/ with that same address and its password? What other steps have you taken to diagnose the issue?