As Darrel and Christopher pointed out already, ExtremeGuest is now separate from the WiNG VX9K Controller and moving forward it will continue to develop and evolve as a separate application. In the following link you will find a collection of How-To-Guides for ExtremeGuest that will help you with your deployment:
As Darrel pointed out, only the NX and VX controllers have database support. Eguest would be the best method for your deployment and there are a few Eguest documents on the portal that covers the WiNG configuration (in your case, RFS4000) and Eguest server.
The ExtremeGuest appliance would provide all of the services you need for the captive portal. Obviously you would need to appropriately configure the guest WLAN on your RFS4000. Prior to WiNG 5.9.2. ExtremeGuest was installed on a VX9000 platform, but has now been separated out to a stand-alone VM installation. I will look for some documentation for you separately ASAP. Many thanks, Darrel.
Interesting. How can I connect the captive portal of an RFS4000 to ExtremeGuest installed on a Virtual machine (VMware). Can you guide me in some documentation. What I found for now concern only VX9000 or NX platform.