Dear bridget chan
Thank you for posting in the Microsoft Community.
I understand that you are unable to configure your two mailboxes in Outlook.
I see that you have selected Outlook Classic in the section. When configuring your mailbox in Outlook Classic, first enter your mailbox name. Then check Let me set up my account manually.
Choose IMAP or POP according to your needs.
Then you may need to use an application password instead of an email password when entering the password. For email security, many email providers require their email accounts to use an application password when logging into Outlook. The application password is usually generated in the settings or security of the email provider's web page. This is a one-time temporary password.
So you need to find it on your mailbox web page, or contact your mailbox provider's technical support. Ask how to generate an application password. You also need to ask what the specific incoming and outgoing server settings are configured in Outlook.
I hope that my reply will be helpful to you.
Best Regards,
Simon.W - MSFT | Microsoft Community Support Specialist