You'll need to make sure you have qmake, g++, the Qt development libraries and the QuaZIP development files installed. On Debian/Ubuntu, this can be accomplished by:

# apt-get install qt5-qmake g++ qtbase5-dev libquazip-qt5-dev libqt5sql5-sqlite

Once the needed packages are installed, create the Makefile with qmake and then build with make. Run the following commands from the directory that contains cen64-qt.pro:

$ qmake
$ make