This problem has been solved!
Thank you for your help!
Here is how to do "Content-Type: application/x-www-form-urlencoded" using the "RestCall" action.
1. General tab settings.
2. HTTP headers tab settings
3. Request settings
*The "Form-Data" and "Export Mapping for the Entire Request" settings caused errors during execution and compilation errors.
You misunderstand the application/x-www-form-urlencoded
header, you should pass an URL parameters here. Check out an example: