Profile Builder Plugiin - how to add customize Login form fields?

Question

I've added custom code to include a "Accept Terms and Conditions" checkbox field that should be required for login. However, while the custom code successfully adds the new field to the login form accessed via domainname.com/wp-admin, it doesn't appear in the login form generated by the shortcode [wppb-login].

Here's the code I'm using:

add_filter('wppb_login_form_bottom', 'add_custom_login_field');
function add_custom_login_field() {
    $output = '<label><input type="checkbox" name="terms_conditions" required> I accept the <a href="your-terms-page-url">Terms and Conditions</a></label>';
    return $output;
}

How can I ensure that the custom field is also added to the login form displayed by the [wppb-login] shortcode?

Thank you!