MailChimp Subscription add-on for WordPress Download Manager Pro gives you an option to add Download Manager subscribers to your MailChimp list directly without any extra hassle. You simply need to enable email lock for a package. So when user will enter their email address to download the package the email automatically will be added to your selected MailChimp list.
Using this MailChimp add-on you can add your new signups to a MailChimp list. The users can be added to different lists based on their user role. It also has support for Premium Package and Pro Membership add-ons. You can add your customers and Membership plan subscribers to pre-defined lists which are very useful for an e-commerce/membership site.
All of the above-stated subscriptions are automated based on user actions ( registration, purchase, download etc ). But if you want to add an optin form for manual subscription. Use this shortcode to place an optin form anywhere you want and select the list for this form in MailChimp settings.