Rules for radio box field

Hello, I need to add a radio box field for privacy purposes.
Basically I want the form to be processed only if a user flag the "yes" radio field, otherwise the user can't register.

How can I do that?

You can do it with a required checkbox, not with radio buttons.

yes of course I was wrong to write, it's checkbox.
However my question was if I can manage something like this:

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Accept the policy privacy:
[] yes -- [] no

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and the form can be processed only if the user checks "yes" (and as default the "no" checkbox is checked).
Please let me know if I can do that or if that requires a payed customization.

You can do it with:
[] yes, I agree
required checkbox.

With Yes/No radio buttons it would require customization, yes.