You will need Sendy App Url, Sendy Api Key and Plugin License Key to get started.
-Plugin License Key: You will get Plugin License Key in email after you purchase Gravity forms Sendy Addon.
-Sendy Url: Complete Url where you have installed Sendy App.
-Sendy Api key: Your Sendy API Key, which you can see in your Sendy App dashboard.
-Sendy Custom Fields: Add Custom Field names separated by comma. These fields will be available in Sendy Feed for mapping with Form Fields
Go to Forms and edit one of your Forms. On the tab click on Settings => Sendy Add-on.
-Click on Add New.
-Feed Name: Give your Feed any name you would like.
-List ID: Enter the List ID to which you want to add contact in Sendy.
-Map the Sendy Fields with Forms fields.
That’s it .. Now when you submit the form it will add new contact in your Sendy List.
You can download the plugin from here