Go to the Office 365 login page. Enter your Email address and password, then click the Sign In button.
Open DUO on your Enrolled Device, select the account and enter the 6 digit Passcode.
Click the Sign In button, and you will be logged in to Office 365.
Login using an alternate device or method
If you would like to log in to Office 365 using an alternate method (push notification or text message) or an alternate enrolled device, you will need to append information to your password when you log in. Complete instructions are available in the Office 365 Email and Calendar Alternate Device tutorial.