Does anyone know how to get this achievement? I get the basic idea, but I've no idea how to set up the game cause I can't load the template.

Old achievement.

First find level 1. GO to https://www.warzone.com/singleplayer/allbuiltin
Pick level 1 and observe the settings / keep the game open.
In a new tab, recreate the game. Place yourself in Austraila.

This link might do it for you https://www.warzone.com/SinglePlayer?TemplateID=12
Swap the slots and you are good to go.

Thank you! This works. Do you know if I have to fight a human player or can it be an AI?

Multiplayer.

Thank you