B-FY uses the biometrics of your phone, the one you normally use. Your phone must have some element of biometric verification, whether it is a fingerprint reader, iris recognition, facial recognition, etc.
If your device has it, you must have a biometric identifier registered in the mobile. If there is no biometric identifier registered, you will not be able to use the app and its functionality.
If you have a biometric feature registered and the app is unable to identify you, please contact us at support@b-fy.com.