(I dislike double-posting, but....)
I think I've at least theoretically sussed out the problem: it might be occurring because I "downgraded" back to Firefox 8 due to the problems that Firefox 13 was giving me (and it's not like Firefox 12 was much better). That seems to be the only reason I can figure while I seem only able to download "index.php" while on here.
That said, going on a hunch about an hour ago, I decided to try downloading via Internet Explorer, and while the file still initially showed up as "index.php", it actually downloaded the .zip file. So I at least have one of the versions now, specifically 2.2.
I wonder if this affects other attachments for me now even though, as I said just above, things were working fine as recently as a month ago. I should probably try to test this with other attachments. If I can, then it's something wrong with the attachments in here (for me)....