Setting MailChimp API:
Go to Dashboard >> MailChimp For WP >> MailChimp >> Setting your API Key then click “Save Changes“. To learn how to get API key, you can refer document of MailChimp.
Create MailChimp Form:
Go to Dashboard >> MailChimp For WP >> MailChimp >> Forms:
Demo Hotel WordPress theme has a style MailChimp form available, just copy and paste below content into your MailChimp form: