Code example for: https://eventespresso.com/wiki/add-course-curriculum-events-using-advanced-custom-fields/

add_course_curriculum_events.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

function ee_course_materials_section_thank_you_page( $registration ) {
  if ( $registration instanceof EE_Registration ) {
    if( get_field('class_courses', $registration->event()->ID()) ):
  ?>
    <tr>
      <td colspan="3">
        <div class="course_materials">
        <h3><span class="dashicons  dashicons-download"></span>Download Course Curriculum</h3>
        <?php while(the_flexible_field("class_courses", $registration->event()->ID())): ?>
          <?php if(get_row_layout() == "course"): // layout: Featured Posts ?>
            <div>
              <h2><img align="right" src="<?php the_sub_field( "course_image", $registration->event()->ID() )?>"><?php the_sub_field("course_name", $registration->event()->ID()); ?></h2>
              <?php the_sub_field("course_description", $registration->event()->ID()); ?>
              <?php if(get_sub_field("course_files", $registration->event()->ID())): ?>
                <ul>
                <?php foreach(get_sub_field("course_files", $registration->event()->ID()) as $cf): ?>
                  <li><a href="<?php echo $cf['course_file']['url']; ?>"><?php echo $cf['course_file']['title'];?></a></li>
                <?php endforeach; ?>
                </ul>
              <?php endif; ?>
            </div>
          <?php endif; ?>
        <?php endwhile; ?>
      </td>
    </tr>
    <?php
    endif;
  }
}
add_action( 
  'AHEE__thank_you_page_registration_details_template__after_registration_table_row', 
  'ee_course_materials_section_thank_you_page', 
  10, 
  1 
);