You must be subscribed to the Sandbox in order to use it for playing or for tentative work. We use this group because all nodes require a group "audience". Use this Sandbox as the audience if you are just playing or if you are not yet ready to publish the nodes you are creating. If you decide to publish your node, you can change it to another group (other than Sandbox), and request that your new node be referenced from some existing node on the Hive.