Maybe your internet connection failed to pass through a firewall or proxy.
I faced similar problems and had to ask my network admin for a temporary direct connection, or install at home. wget was working, but it wasn’t enough for the install.
In latest JetPack release, there is no network tool installed by default (no longer firefox) that allows to perform an identification for some network systems. So it may help to install firefox, or at least ftp, to be able to authenticate later behind your proxy or firewall.