Featured Ads in the middle of the list

Hello. Around a year ago i have made this post.
https://wordpress.org/support/topic/split-displayed-results/

Back then i had no good understanding of WPAdverts internal mechanics, and my client out of the blue wanted again the option to place a featured ad each determined number of ads.

I placed the code of that post that was:

<?php
global $ad_index;
if( $ad_index = null ) {
  $ad_index = 1;
}

if( $ad_index % 3 == 0 ) {
  echo "<div>[FEATURED AD]</div>";
}

include_once ADVERTS_PATH . "/templates/list-item.php";
$ad_index++;
?>

In the list-item.php customized file.

But the result was not as expected
https://imgur.com/a/pBaNEt2

I know that i can set that in the loop for each number i can set something on the loop. Like this example where for a carousel I needed to set an additional counter and once reaches 3 closes the tag and resets such counter.

<?php if( $loop->have_posts() ): ?>
    <?php 	  $loop_counter = 0; $featempty=0;
		      $listings =	count($loop->posts); ?>
	<?php $post_counter = 0; ?>
    <?php $compareb = 0;?>       
    
    <?php
    //Container Height      
        global $heightblock;  
        if($listings <=1){ $heightblock = 206 ;}
        if($listings ==2){ $heightblock = 412 ;}
        if($listings >=3){ $heightblock = 620 ;}
        //echo 'altura'.$heightblock;
    ?>    
    <div class="featuredlist-carousel-vertical adverts-list adverts-bg-hover slider swiper-container">
    
    <div class="swiper-wrapper">    

    <?php while ( $loop->have_posts() ) : $loop->the_post(); ?>
    
    <?php
        if($listings <=3){ echo '<div class="under3-block">';}else{
        if ($loop_counter ==0){ echo '<div class="swiper-slide">';}
        }
    
        include apply_filters( "adverts_template_load", ADVERTS_PATH . 'templates/list-item.php' );
        
        /*echo '<pre>'.$loop->posts[$loop_counter]->ID.'</pre>';
        global $post_id;
        echo '<pre>'.$post_id.'</pre>';
        echo*/
    
        $loop_counter++;
		$post_counter++;
        
        if($listings <=3){ echo '</div>';}else{
            if ($loop_counter >=1){ 
                $loop_counter = 0;
                echo "</div>";
            }
        }
		/*if ($post_counter == $listings){
			echo "</div>";
		}*/
		
        
    ?>

    <?php endwhile; ?>
    </div>
    <?php if ($columns != 1): ?>
    <div class="swiper-button-next"></div>
    <div class="swiper-button-prev"></div>
    <?php endif; ?>
    <!-- Add Pagination -->
    <div class="swiper-pagination"></div>
    <!-- If we need scrollbar -->
    <div class="swiper-scrollbar"></div>

</div>

<?php else: ?>
    <?php            
    $featempty=1; 
     /*
<div class="adverts-list-empty"><em><?php _e("There are no Featured+ ads matching your search criteria.", "wpadverts") ?></em></div>  */ ?>
          
<?php endif; ?>

<?php wp_reset_query(); ?>

In the list.php in this section i know i can do something similar

<?php if( $loop->have_posts() ): ?>
        <?php while ( $loop->have_posts() ) : $loop->the_post(); ?>
        <?php include apply_filters( "adverts_template_load", ADVERTS_PATH . 'templates/list-item.php' ) ?>
        <?php endwhile; ?>
        <?php else: ?>

But i’m not sure how to force that a Featured Ad appears, when the list on the shortcode is limited to only normal ads, and if i go for all, the featured ones goes above in a block.

Thanks in advance, and sorry if i got myself misunderstood.