If you already have an account with Zerodha, you can log in to coin.zerodha.com and then in the search bar you see, just type ELSS or Taxsaver, you will get a list of funds that are tax saver funds. Your investment in these are exempted under 80C of IT act, upto an amount of Rs. 1,50,000
As you can see in the image attached, you can see the investment amount , and returns.
Also you can see, there is an option to download proof of ELSS investments through coin.
Do use the savings calculator tool to see how much you will be saving by investing through Coin, rather than investing in regular mutual funds.