According to the plugin’s readme file, you can call a PHP function in your theme to display the likes, but that includes the buttons. Looking into that function shows the like count is coming directly from post meta, so you can use the same query the plugin uses to get the count:
$like_count = get_post_meta( $post_id, "_post_like_count", true );
In your theme where you want to print the count, you can use
echo esc_html( $like_count );