originally the controller/WLC was a hardware appliance you needed to buy and install in a cabinet.
later Cisco developed a virtual controller/vWLC you could run under VMWare (on a Cisco UCS server) with the same functionality
and last Cisco developed a technique to run the vWLC AND the access point software on a physical access point
the last is called the Mobility Express software image.
(For large environments a physical appliance is still prefered.)
So if you have a physical or virtual controller in your company you do not need to download and run the
"CAPWAP controller based software to configure them",
- you connect the AP to your network
- the AP registers itself to the controller (if network properly configured)
- you login into the existing controller
- from the controller you configure the access point.that pushes cthe configuration to the access point.
if you start fresh in a greenfield, then the you need to som more work.
