If you're having issues connecting to Office 365, below are the three most common things to check.

Troubleshooting Office 365

1) Two-Factor Authentication 

     -Do you use a PIN code to log in? If so, see this guide for more information here.

2) IMAP Settings

     -Check to see if IMAP is enabled under your account settings. 

3) Ask Your Network Administrator

     -Reach out to your email provider or work admin/IT to determine if IMAP is enabled on your account.