That tutorial (I wrote it, and it can be improved a lot, for sure) states in the first sentence:
So you need Tiki13, which hasn't been released yet (it will be, in short, but anyway, I would recommend you to get used to Tiki with Tiki12 LTS (Long Term Support) first.
And about "Admin home", you are right, it's not clear for a new comers where to find it.
Is it better as it is currently written?:
Enable the feature in "Main application menu > Admin > Admin home > Community"
The "Admin home" is also referred in some cases (like the Tiki Setup first screen, once loged as admin in Tiki12+) as "Admin panels"
The documentation is a collaborative effort, so feel free to help the community by fixing the docs. Or at least, reporting the broken links that yuo say that you found.
Thanks and welcome to the Tiki Community!"