How to Use the Laderoboter
William "B.J." Blazkowicz should already be in the Laderoboter when this chapter begins, so bust down the door and start killing Nazis. When the area is clear, shoot the ropes that are causing the bridge to your left to remain suspended (you can do this while inside the Laderoboter), then walk across it and smash the door.
Keep moving forward and killing Nazis, zombies, and anything else that isn't you. The road will hook to the left, and you'll need to go that way since no other path is available. It won't be long until you come to iron gate, forcing you to disembark from the Laderoboter and pull a lever. You can find it in the building labeled "Lagerraum." Just be sure to take a good look around, clearing out any of your undead foes before you turn your back to complete the task.
Tip: Try not to run over Nazi zombies in your Laderoboter. They will climb up and start to cause you damage. You can knock them off, but it's best you just smash them before they get too close.
Pass through the iron gate and smash through the next wooden door. Kill any zombies around, then hop out of the Laderoboter and look for a lit doorway on your right. It's just at the top of a small set of stairs, and inside is the key that will open the small iron gate in front of where you left the Laderoboter. Grab the key, but be sure to spend another moment or two picking up any loot that might be laying around. When you're ready, head back outside and open the gate.
There is one more lever that you need to progress forward, and it's all the way on the other side of the building from where you just entered. Grab your Shockhammer and start working your way through the undead scum that stand in front of you, hooking around to the other side of the building. You'll find the lever over there, and pulling it will allow your Laderoboter through another gate.
Hop back into your Laderoboter and go through the giant iron doors that you just opened. Make your way up the stairs, smashing Nazi zombies as you go. When you reach another wooden gate, bust through it and continue on.
Tip: You should really disembark and spend some time looting the areas that you pass through. There is a great deal of health, armor and ammunition that's just waiting to be taken.
Climb the Wall
After you smash through that wooden gate you're nearly home free. There won't be any additional zombies that you need to kill, but feel free to temporarily disembark from the Laderoboter and spend a moment checking the area for supplies. Wolfenstein: The Old Blood has a habit of hiding some pretty cool secrets around the world they've created for William "B.J." Blazkowicz. Once you approach the statue that's sticking out of the gate and interact with it, the chapter is done.