Unable to download CSV with selenium

I am trying to download CSV data using selenium and python, but not able to do so, also nse website is not returning response for nse option chain website “https://www.nseindia.com/option-chain”. Is there any other work around. I tried google and found url: https://www.nseindia.com/api/option-chain-indices?symbol=NIFTY
Wondering where did this url come from. TIA.
Note -I am new with coding and want to make my data analysis automated…

This site contain bot manager while we try to automate with chrome or firefox we must add the user agent option in the regarding browser option.otherwise we can try with tor browser to automate our process