Instruction to run it and a bug to export

[Toasterme]

I did
pip install -r requirements.txt
python -m streamlit run gridfinity_calculator.py

it will say:
You can now view your Streamlit app in your browser.

Local URL: http://localhost:8501
Network URL: http://your_external_ip:8501

Or you can just go to https://gridfinity-calculator.streamlit.app/

Bug i now have with the online version or mine, is the .scad is opening with OpenSCAD but with errors :
OpenSCAD_Code_5x6_(10.5mm_Left,_2.5mm_Bottom) (1).scad'.
WARNING: Can't open include file 'gridfinity-rebuilt-baseplate.scad'.
Compiling design (CSG Tree generation)...
WARNING: Ignoring unknown module 'gridfinityBaseplate' in file OpenSCAD_Code_5x6_(10.5mm_Left,_2.5mm_Bottom) (1).scad, line 15

There is no file named gridfinity-rebuilt-baseplate.scad

more baseplate.scad.j2
include <gridfinity-rebuilt-baseplate.scad>;

[redRock14]

This is an issue with the way you have openScad configured. In order to render the scad files generated you must have Gridfinity Rebuilt in OpenScad project installed in the proper libraries folder for your openScad instance in your OS.

Look for https://github.com/kennetek/gridfinity-rebuilt-openscad and install that as a module in your OpenScad instance.