Sendiio uses a direct form POST method. You need two pieces of information: your List ID and Form ID.
How to Find Your Sendiio List ID and Form ID
Log in to your Sendiio account.
Go to your Lists and note the list ID for the list you want to use.
Go to Forms and note the form ID for the form linked to that list.
Enter both values in the Sendiio card on the plugin's Autoresponder tab and click Save.
Tip: Sendiio submissions use a JavaScript-based form POST with a controlled redirect. After the subscriber is added, they are automatically redirected back to the funnel's download page. If you experience any redirect issues, make sure JavaScript is enabled in the visitor's browser and that no ad blockers are interfering.