Firstly, there is no zlib 1.2.9 available in the repository. the latest version is 1.2.8. Also I cannot identify the packages that CXXABI or GLIBCXX are contained in. I do have libstdc++6 installed and a number of libc packages such as linux-libc-dev and libklibc. There is no readme so I'm not sure what packages I require as pre-requisites?$ ./FreeFileSync
./FreeFileSync: /lib/x86_64-linux-gnu/libz.so.1: version `ZLIB_1.2.9' not found (required by ./FreeFileSync)
./FreeFileSync: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.25' not found (required by ./FreeFileSync)
./FreeFileSync: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `CXXABI_1.3.11' not found (required by ./FreeFileSync)
./FreeFileSync: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.22' not found (required by ./FreeFileSync)
I have run and update and upgrade on my distro so it should be up-to-date.