Try this:
`
$paged = ( get_query_var( 'paged' ) ) ? get_query_var( 'paged' ) : 1;
$genral_args = array(
'posts_per_page' => '50',
'post_type' => 'documents',
'cat' => 'your-category-id',
'paged' => $paged
);
$genral_query = new WP_Query( $genral_args );
while ( $genral_query->have_posts() ) : $genral_query->the_post(); ?>
<?php
//If we have the posts...
if (the_field ('title')) :
while(the_field('title')) :
the_field('title');
endwhile;
endif;
?>
<?php
$pdf1 = get_field('pdf_1');
?>
<a class="download_button" target="_blank" href="https://wordpress.stackexchange.com/questions/292779/<?php echo $pdf1["url']; ?>">
<li>
Download File
</li>
</a>
<?php endwhile; wp_reset_postdata(); ?>
</ul> `
(change the “your-category-id” to id, or if you want choose more category, use thus: 'cat' => 'your-category-id, your-category-id2'
)