Hello there, Dharmishtha.
It’s possible that you could have used a completely different password and email address to set up your actual site than you did when you set up your WordPress.com account for Jetpack.
You’ll want to log into your WordPress.com account – if you’re having trouble doing so, you can reset the password for that here:
https://en.wordpress.com/wp-login.php?action=lostpassword
Once you’re in, if you go to https://wordpress.com/people, you’ll find a “Download Data as CSV” button under the “Email Followers” tab.
Please let us know if you have any other questions!