Autofill framework is available in Android 8.0 (API level 26) and higher.Autofill option will not be available for android lower than Android 8. Autofill service is still in beta stage.
Enabling Autofill Service
Enabling autofill in settings will open System autofill selection screen. Select Loccker autofill. Or do it mannually by opening the Android Settings. Go to System>Language & Input, and expand the Advanced settings at the bottom. Tap Autofill Service. On the Autofill service, select ‘Loccker Autofill’.
To use Loccker Autofill. Open app to autofill. If autofill detects fillable input field, it will offer option to autofill. Or you can request autofill service by long clicking on input field, then select autofill option. Loccker will prompt for loccker password. After login, loccker will show list of credentials. Select the credential to autofill.