Sorry it took me so long. I just tried to reproduce the steps (on a new Mac) but can't get it to work. From memory here is at least the bit to get your started.
1. Install homebrew (optional but makes the rest easier)
https://brew.sh/
2. Install python3 and pip3
#brew install python3
#brew install pip3
3. CD into the folder containing the script from terminal
#cd /Users/dougjones/Downloads/nparse-0.5.1/
#python3 nparse.py
Now this is working on my 10.14 computer but not on my 10.15. I could be doing something wrong or it could be a dependency thats missing. If you run the script you can share you output here and we can take a look.