In order for us to provide you your subscriber ID’s that have subscribed to your notifications, we need you to provide us the GCM(Google Cloud Messaging)API key from Chrome, and Certificate details for Safari at the time of installation. Without this information, it is not possible for us to provide you the subscriber ID. Also, note to export your subscriber ID’s you need to be subscribed to our paid plans. If you want to know how to register for a GCM key, please refer to the documentation here.