How do I get the hub?

I installed the latest Unity from here

Unity on Linux: Release Notes and Known Issues page-2#post-4458286

And after I have the following when loading Unity

Clicking Install doesn’t actually lead me anywhere.

How do I download Unity Hub and activate my license?

Not sure how you found link to that particular thread.
But try official route

Or simply click Get Unity link.

The website I have looks literally nothing like the capture you have.

Clicking Get Started for Free…

Now, I just want to download the software, but there’s no download… Experienced Users looks to be where I can get a installer…

Oh no, the blog post said Unity for Linux wasn’t beta anymore… except… There’s no Linux download…

My apology, I forgot there is no direct linux download link on official website.
But you have followed right track I suggested and also your initial link to forum.

My other suggestion is check this thread, if you haven’t yet.