You are going to wire up everything per the switch instructions except the door light. It will still have a direct wire from the headlight switch to the tail light filament of the bulb. It will also have a wire from the brake switch to the brake filament of the bulb. This will make two wires from the brake switch. One to the turn signal switch per the diagram and one to the door light.

For the purpose of following the turn signal switch wiring diagram, consider the left and right rear lights as the lights shown on the diagram. The door light is not shown on that diagram.
Feel free to ask any specific wiring questions as many times as you wish. I understand it can be confusing.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn