Various embodiments of the present disclosure are directed to a group-based communication system that is configured to more efficiently manage resource sharing requests. In particular, in some embodiments, the group-based communication system is configured to enable admin users to use an external service, such as an external approval provisioning service, that is separate and distinct from the group-based communication system to manage group-based communication resource sharing requests. In other embodiments, the group-based communication system is configured to allow communication with external users and to trigger new user onboarding protocols through the ingestion of external user directories associated with a sponsor user.