In your case you have to register event "social_group" which is the event type. you have registered event verb.
If you check the system webhooks in this document --> Jive REST Rest API v3.10 → Webhooks service, you have to register the event types like "user_account" or "social_group".
When you register for social_group event type, you will start getting all events with verbs related to social group which are
Haha, that's embarassing. Registering for the "social_group" event worked.
Can I install System webhooks on the Sandbox.jiveon.com or do I need to use a local instance? I have just started with webhooks and was able to filter information for different content types(e.g. document). I will like to fetch events relating to the system. Do I need to use tiles for system events.
Tiles are required only for content webhooks, not system webhooks.
For system webhooks you need to be a super admin so that you can generate the jive signature.
Devs using sandbox.jiveon.com don't have super admin access, so that system cannot be used for system webhooks.
Do you have any preview site for your instance? If yes you can get full access from jive support on that instance (as by default customers don't have it) to test system webhooks.