The basic trap zone setup
When the disc gets swung to the force sideline, the trap goes on. Note that the wing, 6, has joined the cup and the deep deep, 7, has pulled over to help on the throw behind the wing.
When the trap is broken, everybody hustles to regain their positions.
With the disc in the middle, defense 6 needs to float between offense 6 and offense 4, threatening the both throws around the cup
When the disc is on the break side, the cup flattens out. Our goal is now to maintain containment and force the disc to the trap sideline. The cup should be conservative, not trying to poach at the cost of letting the disc through.
As the disc swings to the center of the field, the cup must stay cohesive. Preventing the break is a higher priority than pressuring the disc (although we obviously still want to do that) The mark is flat, and the gaps in the cup small, to ensure the disc continues to move to the trap side.
6 must not get so close to the cup that the offense can easily throw over to 7; if offense's 6 receives the disc close to the cup, that's an OK result that moves the disc closer to the trap. The mark ought to be very flat, almost taking away the dump, to ensure the disc keeps moving towards the trap.