On that Sdr Chille site, when you click Latest, its trying to connect to https://airspy.com/?ddownload=5544 and its not seeing the file. When you scroll down to Friends on the Airspy site, and click SDR# Community Plugin Package, it connects to SDR Chile
It's probably been pulled as most of the (old) plug-ins are retrieved from Vasili's now dead website.
Another reason could be, most of the older plug-ins are probably not working that well in the newer SDR# versions.
I downloaded the community plugin last week when it was on the site but had a helluva time trying to get it to download a few things. I removed a few of them to get it to work after quite a few tries. Probably something to do with why it was removed