To keep the use of the Wallet as safe as it’s simple, it requires your biometric data.
Therefore, please make sure your Face ID or Fingerprint ist enabled in your smartphone settings.
If you’re using an IPhone go to Settings > Face ID & Passcode > Set Up Face ID.
With an Android device, you’ll find them under Settings > Lock Screen and Security > Screen Lock Type > Add your fingerprint.
When your biometrics are set up, simply go to the app overview of your settings, tap on Nuri and enable Face ID or Fingerprint there.