The compilation process by default tries to use the GNU C++ compiler (g++) but it can’t find it on your system, probably because either it isn’t installed or it is in a non-standard location. If the latter, put that location in your $PATH (assuming you are using Linux). If its not there at all, you should install it, or if your system has a different C/C++ compiler, you can use that instead by specifying it in the Makefile (and adding its location to $PATH).