Hello MH Equipment & Ag Resources, thanks for posting this in the community.
May I confirm if you are using a personal account or a work or school account? If it is a work or school account, the Outlook app may require modern authentication or certain security policies. Please update the Outlook app to the latest version, then open Settings and remove any old cached login for this email. After that, try adding the account using the Microsoft 365 option instead of IMAP or POP. If the issue continues, it is possible that your admin has blocked Outlook app sign‑ins, so you may need to contact them to verify the policy.
Kind regards,
John Oli