Returning the name of a category in Wordpress

I have a loop for a custom post type an all is working well, except I cannot return the actual category name that the post has assigned to it.

I have the following code:

<?php
  $posts = get_posts(array(
    'numberposts' => -1,
    'post_type' => 'portfolio',
    'orderby' => 'menu_order',
    'order' => 'ASC'
  ));


  if($posts) {
    foreach($posts as $post) {
      setup_postdata( $post );
      ?>
      <div>
        <div class="mix <?php get_cat_name( ); ?>" ><img src="<?php the_field('portfolio_image'); ?>" alt=""></div> <!-- ACF -->
      </div>
      <?php
    }
  }
  wp_reset_postdata();
?>

This is just one of the WP Codex functions I have tried including tring all with echo. I imagine my problem is something else? Many thanks in Advance.