You definitely have a few options. The easiest, and safest is to use System Setup and choose "One large pool" when you get to the storage page. This will assign all but four of your disks to the first controller and configure the system in an active-passive configuration where the second system is not serving data, but is online and waiting to takeover in case of a failure.
If you really need the capacity of those four disks, there are other options but you'll definitely want to talk to support or your vendor to make sure you end up with a supported configuration.
We had done this on a FAS2020s, but if you slot the 2nd controller in, it gave some error to do with cluster interconnect, and we had to pull out the 2nd controller slightly so its not fully slotted in and 1st controller considered itself a single-controller system. I would suggest maybe don't apply the cluster license and see if that bypasses the cluster/interconnect error.