Verify your phone audio settings are set to maximum so you won’t miss a check in request. Also make sure your phone notification settings are set to Audio On and check to make sure the volume settings are high enough.
There are no custom settings required for Guardian and the application should work immediately without any device changes.
In order to perform a check in, Guardian relies on location services being enabled. This is typically found in the Settings > Privacy or Settings > Location Services options on your device.