First of all, make sure you are in the live_demo directory, then install all the necessary modules with
pip install -r requirements.txt
If on Mac, make sure you are using python 3 as default or use pip3 instead If on Mac M1, make sure you are using a proper environment with Metal.
Once you have installed all the required modules, you can run the server with
python -m main
A window will then open allowing you to choose your framerate (for 2 to 10).