Before doing anything, you need to go to the following link and set up your build environment. Follow the link below:
https://beta.docs.qmk.fm/newbs/newbs_getting_started
Firmware located here (no need to download directly):
https://github.com/qmk/qmk_firmware/tree/master/keyboards/acheron/shark
From this point forward, I will be catering to Windows users, because that's what I am, and that's who I care about. (lame Tommy Boy reference)
Plug in the PCB and wait for the first pop up from Windows device manager. Press the reset button and you should see the STM Bootloader pop up from the device manager.
Next fire up Msys2 and navigate to your QMK firmware directory, which should be like this after you followed the Getting Started Guide:
Once in the root directory for QMK, you'll need to run the actual command to flash the firmware onto the board. It will look like this:
At this point you'll need to press the Reset button located on the bottom of the PCB, then press enter. A successful firmware flash will return the following information:
Another Device Manger pop up will appear but this time listing the Shark PCB.