If you have centralized licensing enabled on a master controller, any other controller you add as a local or backup master (master redundancy), will automatically have centralized licensing and submit and pool its licenses to/from the master.
If you add a controller as a local to the master, it will pool the licenses, then you can add it to your existing VRRP. Access points will be able to connect to the literal ip addresses of the controllers, as well as the VRRP. You can point access points at the VRRP and only the controller that has control of the VRRP will service them.
If you add a controller as a backup master, it will not be operational until the master no longer has control of the VRRP. That means you can only have access points on the master of a master/backup master cluster. You can point access points to the VRRP and only the controller with control of the VRRP (the active master) will service the access points.
I hope that helps...