As mentioned in the comments, the key difference between Mac and Windows here is that scikit-learn requires compilation of C++ extensions, and the build system might be getting confused about which compiler to use. On Windows, it looks for MSVC, while on Mac it should be using clang. It seems that scikit-learn==1.0 is only compatible with MSVC and not clang. Therefore upgrading to a later scikit-learn version is the only solution. scikit-learn==1.0.2 is the earliest version compatible.