won't cause problems with the card payment processing - that's done on another server, and your browser isn't involved in that specific part of the process. The firewall can affect the download though - your computer is being asked to act as a server in those circumstances, and all firewalls will ask for permission to do that.
You turned your firewall off however, so that's not the cause. High traffic on the download server can result in the non-acceptance of your transfer request, but I doubt that this was the case. There's a problem with the card transaction server by the sound of it,so it's almost certainly a Sony problem. If many other people have tried and failed the company should be getting a fair number of complaints, and I suggest that you wait until Monday and then try to contact them by phone.