I tried to install on my Mac ( Mac osx 10.15.7) and obtained:
ehorlait@Rodin Downloads % ./Knowage-6_4_5-CE-Installer-Unix-20191204.sh
gunzip: sfx_archive.tar.gz: not in gzip format
I am sorry, but the installer file seems to be corrupted.
If you downloaded that file please try it again. If you
transfer that file with ftp please make sure that you are
using binary mode.
I tried with version 7 and with version 6 with the same result.