Добре дошли в GTA5-Mods.com

@BakuTheGod It must happen because most likely you didn't install the necessary plugins/mods/expansions correctly. ScriptHookV, ScriptHookVdotNET sometimes can be tricky to install, because the latter has some dependencies (VBasic and VC++ runtimes are needed to run this mod. Check the necessary mods' descriptions carefully and install everything they need. Don't forget to install NativeUI, without it the mod won't work.
Do the installations step by step, I mean install ScriptHookV first, then try running the game. If it works, then quit the game and install ScriptHookVdotNET. Check it. If the game starts up and runs fine, press F10 - a prompt will show up on the top of the screen. If it does, you were successful. Then after quitting the game, install NativeUI and check again.
If everything went smoothly, then you can install the Simple Zombies mod itself. It will work if you could install every dependencies. Good luck!

@emperor thragg Edit the zombiemod.ini file in the \scripts directory, all the settings for this mod are written in this file.

@CentricBeef232 There's a file named zombiemod.ini in the \scripts folder. You can edit that file with any text editor.