Snippet to add a shortcode that displays the media for download.

Display media for download (General)

/**** Custom Shortcode to display media file download link. ****/
/**** Place the following code at the bottom of theme's functions.php file. ****/
/**** Sample Shortcode usage: [ld_download_media_file file_url="https://www.w3schools.com/html/mov_bbb.mp4" file_icon="fa-play-circle" file_title="Some File"]

/**
 * Display the link of the media file for download.
 *
 * @param $atts - Shortcode attributes
 * @return string 
 */
function download_media_file_shortcode( $atts ) {
?>
  <style type="text/css">
    /* Download Link CSS */
    div.file-class {
      background: #f1f4f9;
        border: 1px solid #6f9e94;
        line-height: 2.8;
        padding-left: 20px;
        border-left: 0px solid;
        border-right: 0px solid;
        font-size: 18px;
    }
    a.file-link span {
      padding-left: 15px;
    }
    a.file-link, div.file-class .fa, a.file-link:hover {
      color: #75ceb9;
    }
  </style>

  <?php  
  $file_url  = $atts['file_url'];
  $file_icon = $atts['file_icon'];
  $browser = '';
  $file_title = isset( $atts['file_title'] ) ? $atts['file_title'] : 'Download Now';

  
  if ( isset($_SERVER['HTTP_USER_AGENT']) ) {
      $agent = $_SERVER['HTTP_USER_AGENT'];     
  }
  if ( strlen( strstr( $agent, 'Firefox')) > 0) {
        $browser = 'firefox';
  }

  if( empty( $browser ) )
    $download_att = 'download="'.$file_title.'"';
  else
    $download_att = '';
  
  return $content = '<div class="file-class">
            <i class="fa '.$file_icon.'" ></i>
            <a target="_blank" class="file-link" href="'.$file_url.'" '.$download_att.'>
            <span>'.__( $file_title, 'download_media_file' ).'</span>
            </a>
          </div>';
}
add_shortcode( 'ld_download_media_file', 'download_media_file_shortcode' );