1. Add a snippet "simple-preorder-bootstrap.liquid" with next code:

<script>
    // Bootstrap for Simple Preorder app
    var SimplePreorderBootstrap = {
        "page": {{ template | json }},
        "product": {
            "id": {{ product.id | json }},
            "title": {{ product.title | json }},
            "variants": [
                {% for variant in product.variants %}
                    {
                        "id": {{variant.id}},
                        "inventory_quantity": '{{variant.inventory_quantity}}',
                        "inventory_management": '{{variant.inventory_management}}',
                        "inventory_policy": '{{variant.inventory_policy}}'
                    },
                {% endfor %}
            ]
        },
        "cart": {
            "items": [
                {% for item in cart.items %}
                    {
                        "variant_id": {{item.variant.id}},
                        "product_id": {{item.product.id}},
                        "quantity": {{item.quantity}},
                        "inventory_quantity": '{{item.variant.inventory_quantity}}',
                        "inventory_management": '{{item.variant.inventory_management}}',
                        "inventory_policy": '{{item.variant.inventory_policy}}',
			"properties": {{ item.properties | json }}
                    },
                {% endfor %}
            ]
        },
        // "startupDelay": 100,
        // "productFormSelector": '/cart/add',
        // "productSelector": 'form[action="/cart/add"] [type="submit"]',
        // "variantsSelector": 'form[action="/cart/add"] .variants-selector',
	// "nativeVariantsSelector": 'form[action="/cart"] [name^="id"]',
        // "checkoutSelector": 'form[action="/cart"] [type="submit"][name="checkout"]',
        // "updateSelector": 'form[action="/cart"] [type="submit"][name="update"]',
        // "updateInputsSelector": 'form[action="/cart"] [name^="updates["]',
        // "debug": true,
    };
</script>
<script src="https://preorder.kad.systems/scripts/NAME-OF-YOUR-SHOP.myshopify.com.js"></script>
<script src="https://preorder.kad.systems/script/simple-preorder.js"></script>

Important: At the very bottom of the snippet in the last line, replace the text "NAME-OF-YOUR-SHOP" with the address of your store from the address bar of the browser when you are in the admin area of the store (like "simple-pre-order-demo-shop.myshopify.com", and not, for example, "spo-demo.shop").

2. In the theme template "theme.liquid" right before the closing tag "</head>" add the code to connect the snippet:

<!-- Snippet for Simple Preorder app -->
{% include 'simple-preorder-bootstrap' %}

3. (Not mandatory) In the snippet adjust the selectors for following buttons:

• productSelector — add to cart button
• variantsSelector — list of variants
• checkoutSelector — checkout button in cart
• updateSelector — update cart button

If this does not work, please write to support@kad.systems