Cannot use Blas=Eigen when build pytorch

I try to build PyTorch from sources

I have sucsessfully built it using official instriction,
But now I’d like to build it using Eigen as a Blas implementation.

I run:
BLAS=Eigen python setup.py develop

And in build logs I could see:

image

It tried to find Eigen but couldn’t.

Which more variables schould I set, or how can I install Eigen to make my pytorch notice it.

Linux Rocky 8.8
using conda env - python 3.10
I made conda install eigen (but doubt that it was enough)