Sign in to Office 365 with your work or school account, and password.
After you enter your password, you'll be sent a code to your phone (or to whatever device/app you specified when you set up 2-step verification).
When you receive the 6-digit code, enter it in the box and then choose Sign in.
Tired of typing in 6-digit codes? Use the Microsoft Authenticator app on your smartphone for 1-click verification!