Why you may need PrestaShop PDF Catalog?
You may need to make niche / client / event / seasonal catalogs, brochures and flyers and offer them to your customers on special occasions.
PDF Catalog Creator is Store Manager addon, that means, that it is a part of Store Manager (it is already built-in the software) and should be registered with a separate license key. So in order to use the addon you have to install and register Store Manager and set up all required settings first.
In order to make the process of catalog creation easier you may use Catalog Creator Wizard, which will guide you step by step through the catalog configuration.