Trusona uses the same security method that you use to unlock your mobile device to enable authentications in the Trusona app. If your device does not have lock screen security set up, then you will need to enable lock screen security in order to register with Trusona. Trusona wants to ensure that no one can open the Trusona app and authenticate as you into your accounts if your device gets lost or stolen.
For help setting up a screen lock, see the following links:
Android (Steps may differ based on manufacturer): https://support.google.com/android/answer/9079129?hl=en
If you remove or change your device's unlock method after you registered in the Trusona app, you will need to re-register again in the Trusona app.