A full MAME ROM pack is not just a collection of ZIP files. It requires three tiers:
Use RomVault or ClrMAMEPro with a DAT file obtained from the libretro core’s info page. mame rom pack for retroarch
MAME updates every month. With each update, developers improve the emulation accuracy of a game, which often changes the required ROM files. A ROM that worked in MAME 0.78 (2003) will likely not work in MAME 0.270 (2025). A full MAME ROM pack is not just a collection of ZIP files