Cant get Ajax Load More to work with Astra Theme

Hi, I followed this tutorial: https://connekthq.com/plugins/ajax-load-more/add-ons/single-posts/

Used this code:

<?php echo do_shortcode('[ajax_load_more nextpage="true" nextpage_post_id="%post_id%" nextpage_scroll="true:30" single_post="true" single_post_id="'.get_the_ID().'" single_post_order="latest" single_post_target="#content" post_type="post"]'); ?>

But it doesn’t do anything (no errors) with either single.php or content.php in Astra Theme. What am I doing wrong?