Proceed as follows:

• Get and save one archive file:
  wmm_unix.zip  (UNIX / Linux) or
  wmm_dos.zip  (Windows).
  The files differ with respect to the end-of-line characters only.
   
• Uncompress the archive:
  unzip wmm_unix.zip (UNIX / Linux) or
  pkzip -extr -dir wmm_dos.zip (Windows ...)
  will do (The files have been compressed using the utility zip on a PC running Linux). This should create a directory Wmm containing the C++ mode solver library files, makefiles, a short README file, and a folder Apps with some examples for application programs, C++ main()-files.
   
• For a first mode analysis run, choose one of the example files from Apps, copy it to the Wmm directory, edit it for your own needs, and save it by the name newapp.cpp. Only the file wmminc.h must be included into the main program; it summarizes the header files which are necessary to access the library routines.
   
• Edit the supplied makefile according to the requirements of your compiler. Probably merely the specifications of the compilation command and the compiler options (first two lines) need to be adapted. The file included should work with the GNU  C++ compiler on a standard Linux system (11/2019).
   
• Since the application programs will most likely produce some output files which are not to be mixed with the WMM source files, they should be executed in a separate 'production' directory. Therefore create a directory P in the folder Wmm.
   
• The makefiles have a primary target w, which is to be produced by compiling w.cpp. Hence the commands
  cp newapp.cpp w.cpp
make
cp w newapp
  or equivalents produce the executable newapp. Additionally, the new application must be transferred to folder P, and a copy of the source newapp.cpp may also be useful in P. This is what the script files mo or mo.bat do. Execute the command
  mo newapp
  in folder Wmm to compile your application program (maybe a chmod +x mo is required).
   
• Start the application in folder P:
  cd P
newapp.
  The stderr output channel receives log information: analysis parameters, structure definition, mode solver progress, propagation constant values and file input/output notes. Therefore you might wish to collect this information:
  newapp 2>res.
   

Good luck!