It may have been harsh, but you did a great job!

Some comments:

The deliverable in this lab was main.py – a Python file, but you submitted a Jupyter Notebook (file extension .ipynb). It is important to pay attention to the kind of file you need, because .py are executable via the terminal and you may need that sometimes.

Jupyter is easier to check, because you can run each cell independently, and a .py file runs the whole code, so a suggested workflow is to develop your code on a notebook and then, when everything is ok, click File->Download as->Python(.py) and now you have your code as Python file.