in GM_Zom. NOTHING can get hurt by each other, in ZAPT stuff won't spawn.
you're doing it wrong, in rot's zombies, you must enable friendly fire for stuff to damage something else (player vs. player), and in ZAPT, you have to be near the zombie spawns for it to spawn zombies, with a zombie set on it as a vehicle
they both work, but you just don't bother reading the topics or trying to figure out how to make them work