1) There is no need to install any additional plugin for mailchimp.It is just integrated with mailchimp API key.
You can get the mailchimp api key from mailchimp.com. You need to signup in that site to get the api key.
2) Get into the option Dashboard > Buddha Panel > General > Others > Mailchimp Key there you can put the mailchimp API key and click Save all button.
3) After that you can use the below shortcode where you want to display the newsletter.
[dt_sc_mc_newsletter title=”” listid=”1″ email=”Enter Email Address” button=”Go” show_name=”false”]
You supposed to follow the below steps to create a list id.
Step 1: Get into the site mailchimp.com/playground > Lists
Step 2: When you create a list it generates the list id for your mail id.
Step 2: After that you can create a members under that list who are all subscribe your mail.