Your users are stored in and authenticated against in a Firebase project. WordPress also offers a profile functionality. However, the Fans United platform works only with Firebase. This option gives you the ability to sign in/up the users in Firebase and on success, to copy the user data locally to WordPress.
This means that if the option is checked, each time a user signs in Firebase, their account data (email, name, nickname and password, if available) will be synced to WordPress. This way, the user can use native WP functionalities like comments. Also, all other plugins the client might be using that rely on a WP user, should work seamlessly. If unchecked, only Fans United functionality will work with the registered users.
Keep in mind that we will disable the native WP profile editing screen and redirect the users to the Fans United editing screen. This is in order to prevent the users from editing their data only in WP and skipping the Fans United update. While the plugin is active, Fans United should be considered the source of truth for your user data.