How to roll back to Comodo Firewall v5.x

I personally think v5 is better than v6, but I have upgrade Firewall to v6 and can’t downgrade it. I don’t have a v5 installer and can’t find the download link of v5.
Can anyone help me to setup v5?

https://forums.comodo.com/install-setup-configuration-help-cis/i-need-ciscf-510-or-512-t90635.0.html;msg653192#msg653192