Display a checkbox in KCO that is required to check to be able to complete purchase. This is used for the WooCommerce Klarna gateway (v2).

wc-kco-v2-required-checkbox.php

<?php
// Add a cehckbox to KCO iframe that is required to check before the purchase can be completed
add_filter('kco_create_order', 'krokedil_add_required_checkbox');
add_filter('kco_update_order', 'krokedil_add_required_checkbox');
function krokedil_add_required_checkbox( $create ) {
	$create['options']['additional_checkbox']['text'] = 'I agree to the <a href="https://example.com/terms" target="_blank">terms</a> and data policy.';
  	$create['options']['additional_checkbox']['checked'] = false;
  	$create['options']['additional_checkbox']['required'] = true;
	return $create;
}