Allow your donors to easily opt-in to your cause’s ConvertKit forms and tags when giving. Donors can be added to a specific form that you can set for all donations or on a per-donation form basis.
The Give ConvertKit Add-on provides flexible functionality that allows you to set global and per-form settings for various subscription options. The plugin allows you to select a ConvertKit form and one or more tags that donors will be automatically subscribed to when giving.
Please visit official plugin page for more information