Copy config.example.py to config.py. Configure your destination directory, and your ROBLOSECURITY cookie if you wish to provide one. I would recommend using an alternate Roblox account, mostly out of precaution. Your ROBLOSECURITY is not transmitted to any third party with this script, only Roblox will see your ROBLOSECURITY. Some additional configuration options if you want to configure them are for overwriting the AppSettings list with your own (it could really just be anything with JSON), and a log level if you want to make things a little noisier.

This project uses Poetry, which has very clear documentation on how to install it:

You will need Python 3.12 or later, so install it.. please.

pip install pipx to install PIPX
pipx install poetry to install Poetry under PIPX (You will have global access to Poetry, PIPX performs some gnarly isolation while still allowing global access to tools)
In this directory, run poetry install. This will install all dependencies required by AppSettings-archiver

At this point, execute poetry run __init__.py. This should run AppSettings-archiver, archive all AppSettings channels, and then immediately exit. Your results will be in DST_DIR (by default, 'AppSettings' in the working directory)