You can download the .zip here, then extract it and open QSM.exe
Download SideQuest if you haven't already here, and after doing setup for SideQuest eg. Developer Account on Headset then download BMBF here, install it by dropping the .apk into SideQuest and run BMBF in the headset under unknown sources, go through BMBF's setup.
Then open up QSM.exe and make a desktop shortcut if you want, make sure you plug in your quest into your computer properly using a cable (use the one in the box if you dont have a USB C cable) Open up BMBF in the headset and click whatever you want to download.
Send a message to me on Discord if you have any problems: Juaneth#5381