Can you explain what the purpose is behind wanting to download all of the Mount Orange Demo site?
It is by nature a site designed to use to demo various aspects of Moodle and is maintained as such by HQ - and can be used by anyone as it is, so why set it up somewhere else and have to maintain a duplicate of it?
If you want to be able to demo some of your own added Moodle features then setting up your own demo site would surely be a better alternative, while allowing Mount Orange to remain as Moodle HQ's own unique site without a proliferation of copies of it.
If you want the customised theme, then there have been previous posts explaining that this is More with various customisations - but again, I don't personally think it would be good to exactly replicate Moodle HQ's own site and you should customise your own site the way you want it to reflect your business.
If what you are after is a set of courses to populate your own demo site, then those can be downloaded as Mary has suggested, or you could get some from the community hub, or even use the built in developer tools to generate some dummy courses and users.
My personal feeling is that Mount Orange as a site is Moodle HQs demo site and there is no good reason for them to make the whole site available as a single download that you appear to want.
Perhaps explaining exactly what you are trying to achieve and why would help us give some better hints and tips as to how best to achieve your purpose.