ReferenceError: THREE is not defined

I don’t get it. So is it not possible to use the official version of threejs, to include the 3js code in an external file? It just strikes me as so odd if the correct way to install threejs, is something completely different than what’s on the website itself. Will this, slightly modified version of 3js come back to haunt me later?

And when I do use this other version, I get error “Three.Scene is not a constructor”.

I am having the same question as the author here. But apparently not with the same answer.