Emulators are legal; ROMs are gray area. This guide focuses on the emulator itself and ROM management tools, not pirated game files.
"Final Burn Alpha" (FBA) is a popular emulator for arcade systems, and I'm assuming you're referring to a specific version from 2012. final burn alpha 2012 updated
Ensure your neogeo.zip is placed correctly in your system folder to run any SNK titles. Emulators are legal; ROMs are gray area
libretro-core-info/fbalpha2012_cps1_libretro.info at master - GitHub Emulators are legal