2023.10.6
Done on a MacBook Pro (Apple Silicon). This worked for me, your mileage may vary.
Fork the QMK repository. Clone the repository to your computer.
Install QMK CLI using Homebrew. This takes a long time on an Apple Silicon computer, because Homebrew doesn't have native binaries for many of the packages.
brew install qmk/qmk/qmk
Install the WB32 DFU updater using Homebrew.
brew install wb32-dfu-updater_cli
Run the QMK setup.
qmk setup GITHUB_USERNAME/qmk_firmware -H PATH_TO_LOCAL_QMK_REPOSITORY
Test the build environment.
qmk compile -kb inland/mk47 -km inland
Create your custom keymap in the local QMK repo, in keyboards/inland/mk47/keymaps/YOUR_KEYMAP_NAME
Set the keyboard in DFU mode: unplug the keyboard, plug back into the computer while holding the key in the upper left corner of the keyboard.
Flash the firmware.
qmk flash -kb inland/mk47 -km YOUR_KEYMAP_NAME
Enjoy!