Extract the BSP file to your Valve/maps folder
Extract the skybox files to your Valve/gfx/env folder

The truck prefab was made by Oskar Potatis of TWHL.info
The SUV prefab was made by Viktor-933 of TWHL.info

Map by Goonty (prisonhipster@gmail.com), Goonty #9703 on discord

Notes:
You CAN get into the flying gazebo, it just requires lots of luck