Samsung SM-A405FM/DS User Manual page 150

Settings
Registering fingerprints
1
On the Settings screen, tap Biometrics and security → Fingerprints.
2
Unlock the screen using the preset screen lock method.
If you have not set a screen lock method, create one.
3
Register your fingerprint.
Place your finger on the fingerprint recognition sensor. After the device detects your
finger, lift it up and place it on the fingerprint recognition sensor again.
Repeat this action until the fingerprint is registered.
4
When you are finished registering your fingerprints, tap Done.
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