I believe there is no such “All Categories” archive page natively (because it would be just like the blog page – since every post have a category) . I recommend you to create a page template copying that code and modifying the query to include all posts and then creating a page with the slug ‘category’.
<?php
/*
* Template Name: Category
*/
?>
<?php define( 'WP_USE_THEMES', false ); get_header(); ?>
<div class="archive-meta">All categories of our blog!</div>
<?php query_posts('post_type=post'); ?>
<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
<div class="row">
<div class="article">
<div class="small-12">
<h4><a href="https://wordpress.stackexchange.com/questions/225407/<?php the_permalink() ?>"> <?php the_title(); ?></a></h4>
</div>
<div class="small-12 columns">
<?php the_post_thumbnail() ?>
</div>
<div class="small-12 columns">
<?php the_excerpt(); ?>
</div>
</div>
</div>
<?php endwhile; else : ?>
<?php wp_list_categories(); ?>
<?php endif; ?>
<div class="small-12 columns">
<?php custom_pagination() ?>
</div>
<?php get_footer(); ?>