trying to run a setup script in anaconda, getting error "No module named Cython.Build" after trying to install cython in multiple ways

Question

Apologies if this is a duplicate post, I've looked around and can't figure out why my issue isn't being solved by other answers I've found. Using Anaconda, python 3.9, Windows 10.

I'm trying to run a setup.py script that includes "from Cython.Build import cythonize". When I run setup.py I get the "ImportError: No module named Cython.Build"

I have tried installing with pip, upgrading cython with pip and pip3, upgrading pip and trying again, installing/updating with conda, and I still am getting the error. When I check the cython version (cython -V) I can see that I have Cython version 0.29.28.

I'm assuming and hoping this is an obvious question/answer to someone out there. Apologies again if this is a redundant post, I'm still fairly new and just recently switched to windows/python from mac/matlab.

I also keep coming across a solution to install the Microsoft Visual C++ Build Tools? That doesn't really make sense to me as a solution, but I tried it. It was an 8GB commitment which seems kind of ridiculous.