Are you trying to capture any of the input field values or just to capture the form submit event as a goal?
Either way, if you choose "Form Submit" for the page event, you would be required to specify form ID or name.
So I'd suggest you use something else like "Click" with tagName and HTML5 custom data attributes. If there is a submit button within the Form element, configuration for the page event would be:
Event: Click
Target: tagName: Equals input
HTML5 custom addributes: type Equals submit
You can also consider using "Custome Attribute" instead of "Goal" or "Form".