Thank you for helping me. I have not changed the code of plugins simple-lightbox and advanced custom fields. I realize there is a tag slb_activate, but I can’t understand in which file I need to write it down. I will try to explain a little differently. Using ACF I have added fields to media files, such as additional description, author. In SLB displays standard fields such as name, description, caption. I need to add fields here. In the file SLB /themes/base template output layout.html In it all fields for output looks like {{item.description}}. I can’t understand how can I make {{item.Author}} brought me added the author box. It is difficult to understand the structure of advanced custom fields. I tried adding the code you suggested
$content = get_field( "text_field" );
if ( function_exists('slb_activate') )
$content = slb_activate($content);
echo $content;
in advanced-custom-fields/core/api.php but it gave no result.