Because SM64CoopDX is a PC port and not an emulator, it does not come with Nintendo’s copyrighted assets. You must provide your own legally obtained to compile the game.

Unlike older emulation-based multiplayer mods like Net64, is built on the fan-made PC port , allowing for modern features that original hardware couldn't handle:

How to Play Super Mario 64 Deluxe: Online, 60FPS & HD on Android