Magento – How to show related products in product view page in Magento 2

You name name="catalog.product.related" in your xml and call : <?php echo $this->getChildHtml('related_products') ?>

It should be : <?php echo $this->getChildHtml('related') ?> if your xml is formed correctly. You can also give an alias in your xml like : as="related_products"

In any case, it needs to be a child of the parent node in the xml.

Move the element in your layout xml:

<move element="catalog.product.related" destination="configurator"/>
<referenceContainer name="page.wrapper">
    <block class="Magento\Catalog\Block\Product\View" name="configurator" template="product/view/configurator/configurator.phtml" before="-">
    </block>
</referenceContainer>

In your phtml edit like:

<div id="configurator" class="active">
    <div class="summary">
        <div class="text">
            <h1><?php echo __('Configurator') ?></h1>
            <p><?php echo __("Do the meals come close to what you want, but is there something in the box why it isn't perfect? Here you can edit the meals inside your box, to make the perfect box for you!") ?></p>
        </div>
        <i class="material-icons close-configurator">close</i>
    </div>
    <div class="selector">
        <div class="top-menu">
            <div class="menu-item active"><?php echo __('Meals') ?></div>
            <div class="menu-item"><?php echo __('Ingredients') ?></div>
            <div class="menu-item"><?php echo __('Extra') ?></div>
        </div>
        <div class="content">
            <div class="meal-selector">
                <div class="meal-selector-products">
                    <?php echo $block->getChildHtml('catalog.product.related') ?>
                </div>
            </div>
        </div>
    </div>
</div>

Then redeploy your static files and flush the cache completely.