About controlling the Terms of Service checkbox during sign-up

I’m currently customizing the signup screen based on this article: Customize Signup and Login Prompts. I’d like to implement a checkbox labeled “Agree to Terms of Service” that enables the signup button only when checked. The signup button should remain disabled if the checkbox is unchecked.

I’ve reviewed the official documentation but couldn’t find any relevant information. Could you please guide me through the steps to achieve this functionality?

However, I have already done the following settings.
・Enable custom domain
・Implementation of checkbox using “form-content-end” and

I’m Japanese, so I apologize for the poor English translation.