build issues

[huihuishen]

when I build the code using the code "cmake .. -DCMAKE_BUILD_TYPE:STRING=Release -G Ninja -DCMAKE_C_COMPILER:STRING=clang-12 -DCMAKE_CXX_COMPILER:STRING=clang++-12 -DMJPC_BUILD_GRPC_SERVICE:BOOL=ON"

It failed with the error :

CMake Error at mujoco-subbuild/mujoco-populate-prefix/tmp/mujoco-populate-gitclone.cmake:31 (message):
Failed to clone repository: 'https://github.com/google-deepmind/mujoco.git'

FAILED: mujoco-populate-prefix/src/mujoco-populate-stamp/mujoco-populate-download /home/ss/mujoco_mpc/build/_deps/mujoco-subbuild/mujoco-populate-prefix/src/mujoco-populate-stamp/mujoco-populate-download
cd /home/ss/mujoco_mpc/build/_deps && /usr/bin/cmake -P /home/ss/mujoco_mpc/build/_deps/mujoco-subbuild/mujoco-populate-prefix/tmp/mujoco-populate-gitclone.cmake && /usr/bin/cmake -E touch /home/ss/mujoco_mpc/build/_deps/mujoco-subbuild/mujoco-populate-prefix/src/mujoco-populate-stamp/mujoco-populate-download
ninja: build stopped: subcommand failed.

CMake Error at /usr/share/cmake-3.22/Modules/FetchContent.cmake:1087 (message):
Build step for mujoco failed: 1
Call Stack (most recent call first):
/usr/share/cmake-3.22/Modules/FetchContent.cmake:1216:EVAL:2 (__FetchContent_directPopulate)
/usr/share/cmake-3.22/Modules/FetchContent.cmake:1216 (cmake_language)
cmake/FindOrFetch.cmake:126 (FetchContent_Populate)
CMakeLists.txt:73 (findorfetch)

How can i solve it? (btw. the system is ubuntu 22.04)