You can register for My Medibank online or on the app.
To register for My Medibank, you need to be a Medibank member (ie. have Medibank health insurance). The name you use must be the same as the one you use on your policy.
To register for My Medibank on the app, you'll need to download the app first. Your device needs to be running iOS 12 or above, or Android 7.0 or above.