- Open up Settings, tap General, and then tap Software updates. Apply all available updates.
- Install the Microsoft Intune Company Portal app from iTunes.
- Open the app and sign in using your Azure Active Directory credentials.
- Tap Begin on the "Company Access Setup" Page.
- Click the Continue and Enroll messages until you have completed installation, the last screen should say "Company Access Setup Complete".
- Log into the Intune End-User Portal in a web browser on a desktop or laptop and verify that the device has properly registered and is compliant.
For more detailed instructions with screenshots, see this article from Microsoft.