Last night I dl'd the new installer. Xamarin installers are my fav...the way they pull down all the bits and get it all setup is awesome.
This time I had a couple fails before successfully installing, and wanted to pass along the details in case it'd be of use.
The installer failed to download a couple pieces initially. I would get to the retry button, and clicking it would seemingly try 3x, but in quick succession as if it didn't really try, and then fail. Logs attached.
Quitting and restarting the installer after each fail allowed the process to succeed. Everything is running well now.