You should configure the FaceStation 2 ambient brightness based on the environment it is installed in.
High: semi-outdoors. Device should not receive direct sunlight.
Normal: indoors setting
Auto: Operates similar to high, authentication will take slightly longer than normal but it will be faster than high setting.
Ambient brightness is irrelevant to the registration of the face template.
For instance if you registered the face template on ambient brightness Normal, you can use the same template with ambien brightness setting High.