In addition to our standard downloads and official mirror downloads, LL has graciously provided mirror links for us, as well:
Second Life Status - Newest Firestorm Viewer Download Issues

As a reminder, downloading links from unknown sources — in this case any besides Firestorm Viewer – The Phoenix Firestorm Project Inc., Phoenix Viewer, firestormviewer.rocks, or Linden Lab — is not recommended and is at your own risk.