To be fair, if you go to the downloads section there's a message bar at the top of the page that says
Disabled: SUBSIM Downloads is undergoing routine maintenance, check back later.
so it's not unthinkable that someone would see that and, uh, come back here asking about specific mods that they thought were currently unavailable to download from Subsim (but for which there might be other links at, say, FileFront or some such).
Altho I just tried to download something from there and it seemed to work okay - at least I was able to click all the way through until I got the popup dialog box with download/open/save options or whatever it is. I wonder if that message is a relic from the recent server switch or other issues?