you need a custom handler that uses plutonium client with it not the official one that you can download in nucleus handler browser
i used this guys handler if you want i can send you mines as well
https://m.youtube.com/watch?v=n7-d1vr8F3M
There are other ones you can try too
https://m.youtube.com/watch?v=wtMqK8umW8U
https://www.reddit.com/r/CODZombies/comments/1nvfsqr/pc_users_you_can_play_zombies_splitscreen_too_on/
