Download the file. And extract it. Make sure you have menu backgrounds (https://modworkshop.net/mod/17160) watch a video if you don't know how to install mods (https://youtu.be/AtdN6-R95_w)
Then move this into the menu backgrounds folder. Then move it into assets in the menu background folder and launch payday.
Go to options then mod options and chose Safe house menu background (you can rename it if you want by going into the folder and just changing the name)