Hello Aditya

Contact the Narayana directly or ask your friends or seniors, who must have used the material before to get the Narayana CDF for JEE. Sometimes, students share materials through such platforms as Careers360. You can further ask people there. You may also check nearby bookstores or online educational resource sellers, who would sell you the material. If you need general study material for the JEE, then you also have packages such as the Careers360's JEE Knockout Package available to you.