It looks to me like you have it already with
<?php the_field( 'add_featured_image', 'category_6' ); ?>. It's just outputting an object from which you have to get the
$url = $add_featured_image['url']; and then echo it out into your image
<img src="<?php echo $url; ?>"/>. Same method then to get the
You'll see more here.
Hope that helps. Best of luck!