Add an email account to Outlook
https://support.office.com/en-us/article/add-an-email-account-to-outlook-6e27792a-9267-4aa4-8bb6-c84ef146101b
*Microsoft had stopped supporting and retire Basic Authentication for Exchange Active Sync (EAS), Post Office Protocol (POP), Internet Message Access Protocol (IMAP), and Remote PowerShell (RPS) in Exchange Online after October 13th, 2020.
Please refer to: https://developer.microsoft.com/en-us/office/blogs/end-of-support-for-basic-authentication-access-to-exchange-online-apis-for-office-365-customers/