Zombie Pillage / 2 Players

[EvilNed]

We played Zombie Pillage last night, but the zombies won on turn 6 or 7, and we realized we must have played it wrong.

First off, we let the zombie players each play seperate turns. But when it came down to Pillaging, this meant the zombies got to pillage almost twice as much.

We realized there could be any number of solutions to this, but the rules didn't state which one was correct. So,

Do all zombies move at the same time, regardless of how many players there are?

Or

Do the first players move their zombies, then the second player? In that case, is the entire turn done this way, or just the individual phases?