Couldn't access Zammad UI on localhost but works using Proxy URL

@MrGeneration I think I haven’t explained my question clearly.
In general, I want to access Zammad in port 80 which is the default port for which Apache listens to. But in my case I am accessing it on the port I set manually on Proxy. If that is how it works fine, I just didn’t understand the Proxy (URL, PORT). In conclusion, Zammad will be accessed in Proxy URL and PORT instead of on default HTTP (80) OR HTTPS(443). Correct me if I am wrong.