WooCommerce.com is a marketplace of plugins that add extra functionality that is not included in the free WooCommerce plugin. Since these plugins “extend” the core functionalities of the free plugin, we call them extensions.

Since these are paid premium plugins not available in the www.ads-software.com repository, you won’t be able to find them through the Plugins page of your wp-admin dashboard. To install them you have to purchase them on WooCommerce.com, and then you’ll receive the plugin files to install on your website.

You can read more about that Pinterest plugin in the documentation pages here.

I hope this helps clarify things!