If you use the Uni-BIOS, you can hold down button A+B+C during the startup screen to enter the BIOS menu and change the region and settings. Conclusion

Until such projects mature, the Universe BIOS offers a practical middle ground: it is distributed with permission from its author, and the free version is sufficient for most users.

You must place neogeo.zip in the designated folder where MAME looks for games.

Use your arrow keys to change the default BIOS to .

What or retro frontend (like RetroArch) do you have installed? What specific error message are you seeing on your screen?

MAME is far from the only emulator that can run Neo Geo games. Depending on your platform and performance requirements, you may prefer one of these alternatives: