Connecting Fluent Forms to Laposta
With the add-on by Jos Waalkens, submissions and newsletter sign-ups from your Fluent Forms forms are forwarded to a list in Laposta. Jos Waalkens is an external party. The add-on is similar to the Mailchimp add-on.
You can find prices, instructions and the current options on the plugin page on Jos Waalkens’ website. The same developer also makes an add-on for Gravity Forms.
For an overview of all integrations for WordPress, see Choose a WordPress plugin.