I'm not really sure what is being referred in regards to the "subscription request with account". The way that the FedEx shipping quote server behavior works it needs an account and meter number. You should already have these available to you when you start with the checkout wizard or apply the FedEx shipping quote server behavior. Looking around on FedEx it seems that you need to register a developer account to obtain the proper credentials. Once obtained you just enter these values into the checkout wizard or the shipping quote server behavior.
Have you signed up for a FedEx developer account? This is the first step, it looks like they give you some test credentials and after you run a couple of tests you get the live credentials. You should not need the test credentials for the shipping quote server behavior, you should request a set of live credentials for this.