Unknown CMake command "rigid_ipc_download_project"

[WenqiangX]

Hi, I git clone the rigid-ipc, and use python build.py to compile the project.

It gives this error:
CMake Error at python/CMakeLists.txt:6 (rigid_ipc_download_project):
Unknown CMake command "rigid_ipc_download_project".
Call Stack (most recent call first):
python/CMakeLists.txt:13 (rigid_ipc_download_pybind11)

my cmake version is 3.16.3
os: ubuntu 20.04
python: miniconda with python 3.7

BTW, I also tried with:

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
make

This can make with no mistakes.

I think something wrong with the python part?
Any suggestions? Thanks!