install retroarch and flycast
throw the naomi.zip bios into ~/.config/retroarch/system/dc/naomi.zip
load the game, open the Quick Menu, go into Core Options, Video, and change Alpha Sorting to "Per-Strip", adjust other options as needed, you probably want to disable fog and mipmapping because they make the game look like garbage.
adjust button mappings, they should be:
R_trigger	ACCEL
L_trigger	BRAKE
B (bottom)	REVERSE_GEAR
A (right)	DRIVE_GEAR
START		START
SELECT		COIN
(or map START and COIN to X and Y if you like)
L_ANALOG_LEFT	HANDLE-
L_ANALOG_RIGHT	HANDLE+
map the test/service buttons to whatever you want (ideally something you don't accidentally press), they are for maintenance and configuration so don't press t
hem while you're playing or you'll throw away your run.
enter the service menu and navigate through it with the test/service buttons, navigate to GAME TEST MODE, VOLUME SETTING, and calibrate your analog controls, you should calibrate deadzones in retroarch first and not correct them in the service menu, it's meant for arcade machines, so just set the lowest/zero/highest positions to 00/80/ff.
exit retroarch from the option all the way down in the main menu (don't just kill the window) so it actually saves your config, now restart it and have fun!
i included button mappings for a gamecube controller hooked up to a USB adapter, this goes into ~/config/retroarch/autoconfig/ in case you want something as a reference or have a gamecube controller with an adapter.
honestly, gamecube controllers are the best controllers ever made, especially for this game.