Integer supports MailChimp for WordPress plugin that lets you connect your website with Mailchimp.
Follow the steps below to add subscription forms to the end of each post.
Step 1. Make sure that MailChimp for WordPress is installed. Follow this guide for installation instructions.
Step 2. In your WordPress dashboard navigate to MailChimp for WP → Forms
Step 3. Paste the code below to the form editing area and click Save Changes.
Optionally change text messages, to something more related to your website.
Step 4. Navigate to Appearance → Customize.
Step 5. Open the Widgets panel and choose After Post Content
Step 6. Add MailChimp Sign-Up Form widget to the After Post Content widget area.
Step 7. Remove the Widget title and click Save & Publish.