Netflow does not supported on vWLC.
Here are the restrictions listed on 8.3 config guide
http://www.cisco.com/c/en/us/td/docs/wireless/controller/8-3/config-guide/b_cg83.pdf
• The enhanced template is not supported on the Cisco 2504, 5508, 7510, and WiSM2 WLCs.
• NetFlow is not supported on Cisco Virtual Wireless Controller (vWLC).
• FlexConnect mode is not supported.
• IPv6 traffic is not supported.
• Only one collector and exporter each can be configured.
Refer below for more detail about netflow support in AireOS 8.2 code
https://mrncciew.com/2016/12/19/wlc-netflow-with-aireos-8-2/
Remember that only 8540/5520 supports this enhance flow format introduced in 8.2 onward.
HTH
Rasika
**** Pls rate all useful responses ****