There you’ll find all the information you need to know on how to properly edit Shopify’s email template.
Customily stores the production file URL in the order properties, so you can easily access it through the line item properties. In this case, the specific property for the production file is called:
"_customily-production-url"
Here’s an example of how you would use it in the order confirmation email template from your store:
{% if line.properties['_customily-production-url'] != blank %}
{{ line.properties['_customily-production-url'] }}
{% endif %}
Keep in mind
The email confirmation template may vary from store to store. You have to find the line in your Shopify template where the product item is inserted and add the production file URL in the right place.