FreeFileSync Forum

FreeFileSync requires a gui. There's no cli only mode. Therefore, you need to install X (sudo yum install xorg-x11-server-Xorg) and gtk to make it work. If all that makes your head spin then it's just easier to install your favorite desktop environment (gnome, lxce, kde) or switch to alternative ...

The problem is, FFS doesn't compile with GCC 4.8 that is shipped with the latest CentOS, same problem for OpenSuse. Then both these OSes have far less users than Debian and Ubuntu which ship GCC 5.2. So official pre-compiled version will probably be available again, but not before the next OS ...