I am a client of Zerodha, can i use Amibroker plugin on NSE Now platform? If yes then how?

You will need to subscribe to data feed from GDFL to get the Ami plugin. Check out these links

http://zerodha.com/main/zerodha-trader-plugin-amibroker.html

http://www.globaldatafeeds.in/global_datafeeds-offer_to_zerodha_users.html