Download the DUO app from the App Store.

Duo Mobile for iPhone

When you enroll in Duo for the first time and choose to add an iOS device or use Duo Push, you're shown a QR code to scan with the Duo Mobile app to complete activation.

If you would like to add an iPhone after you have activated on a different device you can go to the SPS Portal and type your name and password. When you are prompted by Duo you can select "Add a new device" from the settings menu, follow the prompts and you will be presented with a QR code to activate Duo on your phone.

Launch Duo Mobile and step through the introduction screens.

To proceed with adding your initial Duo account to Duo Mobile, tap Use a QR code. Use your camera to scan the QR code shown by Duo Enrollment in your browser. If you're prompted to allow Duo Mobile permission to use your device camera, please grant it. 

Name the account "SPS 2FA" to complete adding your account to Duo Mobile. For more advanced settings refer to the link under "Enrolling in DUO with an iPhone" at the top of the page.