There are some cases where you may not want the Submit button to show on a Web Form until certain conditions are met or the resident pre-qualifies by answering certain questions.
You will see a gear icon next to the Submit button that will allow you to customize just as you might a normal field:
Then in the customization window you can enable Conditional Show/Hide and have the Submit button hide or show based on previous selections:
You can even customize the message that shows when the button is disabled so that users understand why they are unable to submit.