In order to get AP assisted location tracking working with the NX and VX controllers, the WiOS controller must be enabled so that RSSI data can be passed to ADSP. There are procedures for BSSs and Wireless Clients tracking. Refer BSS Tracking and Ciient Tracking.
Note
This is only for the controller infrastructure. The 5.x version of APs do not require this sort of configuration. The Cisco WLC does not require configuration to enable AP assisted location tracking.