infinite scroll

I tried to add infinite scroll )https://www.billerickson.net/infinite-scroll-in-wordpress/) in my page but is not working. is there any plugin or script works with this theme?
https://www.susanflory.com/podcast/

<?php
/**
 * Template Name: podcast
 */

get_header();
?>

<main id="site-main">
	<?php
$paged = ( get_query_var( 'paged' ) ) ? get_query_var( 'paged' ) : 1;
$args = array(
  'posts_per_page' => 12,
  'paged' => $paged
);
$custom_query = new WP_Query( $args );
?>

<?php $episode = get_field('episode'); ?>

	<div class="site-page-content listpodcast">
		<div class="site-section-wrapper site-section-wrapper-main clearfix">
			<div class="searchbar">
			<h1 class="floatleft">Episodes</h1>
			<div class="floatright"><?php get_search_form(); ?></div>
			</div>
			
			<ul class="lastfive">
			<?php
			   while($custom_query->have_posts()) :
				  $custom_query->the_post();
			?>
			

           <?php //$backgroundImg = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), 'thumb-featured-podcast' );?>
            <li>
				<div class="box">
				<a href="<?php the_permalink() ?>">
				<div style="background:url('<?php echo $backgroundImg[0]; ?>') no-repeat center center; background-size:cover;">
					<?php the_post_thumbnail('thumb-featured-podcast'); ?>
					<!--h2 class="episodenumber" >Episode <?php the_field('episode', $episode->ID); ?></h2-->
				</div>
				<div class="pd15">
				
				<h3><?php echo wp_trim_words( get_the_title(), 12 ); ?></h3>
				<h4><?php echo wp_trim_words( get_field('episode' ), $num_words = 30, $more = '...' ); ?></h4>
				<!--p><?php echo excerpt(30); ?></p-->
				<p><em><?php echo get_the_date() ?></em></p>
				
				</div>
					</a>
				</div> 
			</li>
              <?php endwhile;?>

  <?php if (function_exists("pagination")) {
          pagination($custom_query->max_num_pages);
      } ?>

</main><!-- #site-main -->
	
<?php get_footer(); ?>

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