To log in using Touch ID, you require an iPhone 5S or better with iOS version 8 or higher and a password for the Safe (see Setting or changing your password). At least one fingerprint must also be registered in the settings of your iPhone.
Open the Safe app on your smartphone, enter the contract number (if not previously entered) and select "Login with Touch ID". When logging in for the first time, you will need to accept the terms & conditions.
Please note that you can only configure one Safe account for logging in using Touch ID on your smartphone.