Hi
From my setup (similar setup as you are running) - It mostly comes down to how Redundancy is setup and the Roles you are running on them.
From my setup, on the GUI under Controller Configuration your Backup/Secondary Controller should register the Role as "Standby" and your Primary will have the Master Role.
On the Secondary if it is in the Standby Role then your centralized licensing options should be greyd out and unconfigurable on the Standby/Backup/Secondary controller. Meaning you only set it up on your master with the apropriate VRRP ID - the secondary should dupilcate the Configured license redundancy from your Master.
How my Redundancy is configured - on mine I have the VRRP route between the 2 controllers + Database Sync enabled + Master redundancy config running on the created VRRP ID.
From the NOTE displayed on the Controller GUI below the Centralized License Config it states:
This Config will be used if this box is a Master/Backup license server
License Server Redundancy is already available since Master-Standby redundancy is configured.
License Redundancy and License server IP are only applicable in an all Master Controller deployment.
Hope this helps