I just downloaded adobe air and it says downloads not available. What should I do?

The 2.0 download won't become available just because you downloaded Adobe AIR (although you do need it to run 2.0).

The issue is that the certificate (a way servers prove their identity) for download.scratch.mit.edu (where the 1.x and 2.0 downloads are hosted) expired and the ST hasn't renewed it yet, so browsers think it's insecure. To get around this, just visit https://download.scratch.mit.edu and click/tap past the warning screen, and let the page load. You should then be able to download 2.0.

Thanks for the avice!