I've been wanting to install the 2.0 offline editor to my PC for a while now. Why?
Simply nostalgia, I just want to relive the feeling of 2017 when I first originally joined.

But I can't install the editor. It says that downloads aren't available now, and it's been saying that message for a long time.

What's going on and why isn't it available?

https://scratch.mit.edu/help/scratch2download/
the links there still work.

The downloads are available, also read the stickies:
https://scratch.mit.edu/discuss/topic/743454/ (this question is included in the directory in Temporary Questions)
This is happening because of the certificate where the files are hosted expiring. If you get an error on the page, try going back to the download page, and then refreshing).
For the Adobe Air link, you can go to the new download page.

Oh, okay. Thanks for the help, and I'll report this to be closed now.

The certificate (a way servers prove their identity) for download.scratch.mit.edu (the subdomain that holds the 2.0 and 1.x downloads) has expired and the ST hasn't renewed it yet.

In addition, the main page seems to be returning a HTTP 417 error.

You can still download the files by going directly to the pages that have them, and clicking past the warning screen. These pages are:
https://download.scratch.mit.edu/scratch2download/sa/Scratch-461.dmg (Macs)
https://download.scratch.mit.edu/scratch2download/sa/Scratch-461.air (Macs w/ Mac OS 10.5 & older)
https://download.scratch.mit.edu/scratch2download/sa/Scratch-461.exe (Windows)

Also make sure to follow the other instructions on the 2.0 download page to make sure that it will actually work (2.0 ran on the Adobe Flash player, which has since been deprecated and discontinued, so newer computers simply don't have it downloaded)

ninja'd- I spent too long writing

Glad you found an answer! Since this is resolved, I'll close it to help highlight the answer and prevent future responses. If you need it re-opened, though, you can report this and ask.