I'm afraid there is more to it than that. The Lib64 map that has been created under the FDS map in the Downloads folder may have it's contents at least linked to another map and the command line
mpirun -np 8 fds5_mpi_linux_64 Scale1.fds must at least be changed to mpirun -np 8 fds5_mpi_linux_64 scale1.fds (it will just not run with a capital S)