This skeleton repo requires to be populated with the licensed MUMPS source code. The folders with CMakeLists.txt files mirror where they need to be within the source tree of MUMPS.
The main complexity of compiling MUMPS on windows with cmake while retaining your mental health is extracting the build of libdmumps etc from src/Makefile. This is done with the parser project in ./buildutilities. To run it, simply install the dependencies and run python Driver.py repopath/src/Makefile and a template CMakeLists.txt is genereted in your current directory. This build worked for MUMPS 5.7.3.
Simply download your version of MUMPS into the folder, i.e. the content of src into the src folder etc. THEN run the cmake on your source and it should simply work.