Hi, just start up the game, in Mods select ZM Bots, then in Zombies, just click on Private Game, select the map you want to play on, and just start it. Make sure you have Player Limit on higher than 1. You can check that while you are in the Private Game lobby, by clicking on the bottom right corner on Social, then on Manage Party. I hope I could help.

its not showing in my mods

Same issue any fix

Works fine for me...