The easiest way to build the program is with CMake.
First you need to install all required dependencies.
You can do this with sudo apt-get install cmake wiringpi build-essential libmosquittopp-dev.
Then, all you have to do is create a new folder with mkdir build in the current project folder, change to this folder with cd build and create a makefile with cmake ...
Then you can create the executables by simply typing make
Now install the program with sudo make install.