The other player joined through player invite in the top right corner. Once they accepted the invite they had to wait for the first player to set everything up and hit ready before their screen turned to the ready screen. It isn't the most convenient flow but it works.
![World War Z: Aftermath Coop Playthrough [Part 2]](http://i.ytimg.com/vi/bRpfy3EEvL4/mqdefault.jpg)
![World War Z: Aftermath Coop Playthrough [Part 2]](/img/tr.png)
How did the other person join
The other player joined through player invite in the top right corner. Once they accepted the invite they had to wait for the first player to set everything up and hit ready before their screen turned to the ready screen. It isn't the most convenient flow but it works.