Virtualmin GPL

I have a question regarding Virtualmin GPL:

I was able to customize the â

There’s a way to show a custom error page when you disable a site? Tell me how!
When I disable a site, it just doesn’t load on the server anymore…If I could show a page stating non-payment or something similar, I’d be thrilled…

Only the paid version has this feature. The GPL version one simply disables the website.