I successfully ran ZS in my old laptop but when i access its web GUI https is broken. I believe it has something to do with its SSL certificate(if im not mistaken).
Is there something i can do to fix it? except adding it as exception on my browser.
This is the browser issue. The browsers believe that everyone must pay $$ to Verisign etc and buy their certificates instead of generating their own. This monopolistic arrangement is the reason why you see a warning about the self-signed certificates.