App Lock
From the app’s English Help & Guide · Reference release 1.0.3
Open More → Preferences and turn on App Lock to require the authentication method offered by your device before Documented opens.
Auto-lock
When App Lock is enabled, choose how quickly Documented should lock after it moves to the background.
Biometric privacy
Authentication is handled by iOS. Documented does not receive or store Face ID, Touch ID, or device-passcode data.