Mesh files are large and not version controlled. You can download them here (you'll need to be logged into your SU OneDrive account for access). Then extract the zip archive into a sub-directory of this repository named "meshes".
You also need to install the PyBullet simulator.
Once PyBullet is installed and the meshes are extracted in the correct location, you can visualize the simulation environment. Run this command from within the top-level folder of the repository:
python simulation.py