Prior to publishing, head to the right side-bar in the Clip Organizer. The Visibility field under Property Info offers the option to set the tour to Public (default) or Hidden. Public means that as soon as the tour is published it will 1) be in the VR marketplace app and 2) have live web tour links. If Visibility is instead set to Hidden, only the web tour links will be live and the tour will not yet be showing in the VR marketplace.
Web links for tours set to Hidden can be shared with listing agents for their review prior to having the tour go live in the VR marketplace. Once the tour is ready, Visibility can then be updated to Public and the tour re-published so that it is viewable both on the web and in the VR marketplace.