Add follow author button in each type of post automatically

wpfmbp-follow-author-in-post.php

<?php
  /**
   * Add author follow button in each post
   */
  function wpfmbp_add_author_follow_in_post( $content ) {
    
    global $post;
    
    if( isset( $post ) ) {
      
      $author_id = $post->post_author;
      
      // Add button on Top
      $content =  do_shortcode( '[wpw_follow_author_me author_id = "' . $author_id . '"]' ) . $content;
      
      // Add button on Bottom
      $content =  $content . do_shortcode( '[wpw_follow_author_me author_id = "' . $author_id . '"]' );
    }
    
    // return content
    return $content;
  }
  
  // add filter to add follow author button
  add_filter( 'the_content', 'wpfmbp_add_author_follow_in_post' );
?>