acf-gallery-lightbox.php

<?php 
            $images = get_field('floorplans');
 
            if( $images ): ?>
                <div id="slider" class="flexslider">
                  <div class="col-md-3">
                    <?php foreach( $images as $image ): ?>
                            <a href="<?php echo $image['url']; ?>" data-lightbox="floorplans"><img src="<?php echo $image['sizes']['medium']; ?>" alt="<?php echo $image['alt']; ?>" /></a>
                    <?php endforeach; ?>
                  </div>
                </div>
            <?php endif; ?>