Instructions are in the page but the short of it is making a patched folder in system/fbneo (it must specifically be called “patched”) then putting the roms in there, removing the extensions and matching the original rom as need be, there’s also a text doc for marking what each rom is and what base rom you need.
This is mainly good for Libretro since standalone uses dat files, the original IPS archive is good for that since I’m nearly done putting in the dat files for that, there’s also instructions in there on patching yourself for Libretro but this is for skipping that step.
It also has instructions if your using it standalone too. Though it has not been tested with any version of Fightcade, your welcome to try but don’t expect the most success