missing privacy api
your plugin appears to pass the users firstname/lastname and email to an external service Plugins that integrate with external services must implement a valid privacy api class for approval in the plugins db.
take careful note of the external_location_link function - this is the one you will need to implement in your privacy api class as per: https://moodledev.io/docs/apis/subsystems/privacy#indicating-that-you-export-data-to-an-external-location