I see what you mean, I think @staff ought to update this part of the docs which give the wrong impression:
Provide a domain like example.com. The way Cloudron works is that the dashboard gets installed at my.example.com, and apps are installed under subdomains that you specify like git.example.com, chat.example.com, and so on.
But by looking closer at the demo, I can see how the location can be changed (app's location tab) - so I assume that's how it's done.
Yes, you can always change location there, but you can also just directly install on the root domain in the first instance too.