You should be able to get around this by going to portal(dot)office(dot)com/account. Click on Security & Privacy, then Additional Security Verification and Create and Manage App Passwords.
Create an app password. This password bypasses 2FA and can be used simultaneously across multiple browsers and/or machines.
Works great for us. I have 23 users on 2 accounts. They use Outlook (desktop), Roundcube, OneNote, and Sharepoint regularly.