With the storm door closed, on the inside of your door, place the dotted line of the template against the Z-Bar.
The z-bar is like a door stop however, it is narrow which allows the inside latch to pop out behind it.
If installing on a screen door, before drilling holes, hold the inside latch up to the placed template and ensure the spring loaded catch clears the door stop and there is room for the proper installation of the strike plate.