Navigate to the Emails & Actions tab then select Add new Action
Select the Success Message action
You can rename the Success Message action by changing the Action Name.
Input the information that you would like to display to the user when the Success Message is processed.
Adding all field data to the Success Message
Like with the Email action, you can use the “All Fields” merge tag to add ALL of the form data to the message.
Adding single fields of data to the Success Message
Click the “carrots” icon to change the rich text editor into an HTML editor.
When done, press the done button.
The action can be enabled or disabled using the toggle.