Duo Passcode Authentication Duo has many forms of authentication available, including Duo Passcode Authentication. The Duo Security app on your phone can generate a 6-digit passcode that can be used to log into Marquette’s Microsoft 365 (Office) applications via the web. This method can be used with or without a connection to cellular data or Wi-Fi. Follow these steps to use a Duo passcode. When prompted for login credentials at the Microsoft 365 login page, enter your Marquette email address and the password for your account. The "Choose an Authentication Method" screen will appear. Click or tap the Enter a Passcode button, and an input field will appear. Go to the Duo mobile app on your registered device and tap Show next to the passcode. On your device, a 6-digit passcode appears. Type that 6-digit passcode into the Passcode input field from Step 2. Click or tap the Log In button to complete the process. Just to note, the Duo passcode can be generated with or without cellular data or Wi-Fi.