Cmake error when installing.

I'm getting this error when installing. Not sure if it's an error in the steps of the installation or a result of my lack of knowledge in Linux. Installed Linux in Virtualbox to try the program.

Cmake error at CmakeLists.txt

The Cmake_C Compiler.

Path_to_emsdk/upstream/emscripten/emcc

is not a full path and was not found in path

Tell Cmake where to find the compiler by setting
either the enviroment variable "CC" or the Cmake
cache entry CMAKE_C_COMPILER to the full path to
the compiler, or to the compiler name if it is in
the PATH.

Start with the installation steps and CMakeLists.txt, then reproduce the configuration error in the Linux VirtualBox environment. Check how the emsdk emcc path is supplied to CMake through CC or CMAKE_C_COMPILER. Done means the project configures without the missing-compiler error and the installation can proceed.

Written by the indexing model from the issue text.