can't install quickbooks 2015

Hi, I'm trying to install Quickbooks Enterprise Accountant 2015.  I get a messaging saying that it needs to verify my subscription before installing quickbooks, but was unable to reach the quickbooks server, therefore quits the installation.  At first I thought it might be my antivirus / firewall preventing the app from contacting the server, but after turning these off I still get the same message.  I know that 2015 software is "no longer supported" by intuit in terms of updates, but does that mean that you have also turned off the 2015 verification server?  So that it can no longer be installed?  Or is there likely another cause of this error?  Thanks