Have tested on an imac with latest El Capitan and a macbook with Maverick and I am getting the same result.
Went to create a new card using the installer and it lets me input language and device but when I try to go on I get an error message " There seems to be an issue connecting to the network . Please check that that you are not trying to download OSMV via a proxy server." The installer then fails to offer any version to install.
I am not using a proxy server in fact nothing has changed on my network at all and I never had this message before and have successfully created many cards in the past.
Has something been changed on the installer?
I have tried allowing the installer as a recognised app on the Apple firewall but that made no difference.