Output custom HTML anywhere on the CheckoutWC WooCommerce checkout page.

output-custom-html.php

<?php
/**
 * Output custom HTML below the CheckoutWC cart summary
 */
add_action( 'cfw_after_cart_summary', function() {
	?>
	<div class="example-container-class">
		<h2>A heading!</h2>
		<p>A paragraph tag.</p>
		<p>A paragraph tag with inline PHP: <?php echo 'Inline PHP!'; ?></p>
	</div>
	<?php
} );