Implementing Limitations

We want to globally set limits for
-  maximum number of Groups allowed per subscriber
- maximum number of members allowed in each Group

Please advise. 
 

- maximum number of Groups allowed per subscriber

That's doable by creating a Number field then within CB GroupJive > Parameters > Groups > General set "Create Limit" to your Number field. Now you can increment that field using CBSubs or whatever method you like to adjust their group create limit.

- maximum number of members allowed in each Group

There's no functionality for maximum group users in GJ.