Thanks for following up about the @ArtseePresets
Shopify does not have the ability to connect digital products for download to an order without the use of an app. It sounds like you may have 2 separate apps working in tandem, hence why you are seeing two separate emails.
In your store admin under Settings > Apps and Sales Channels you can review the apps installed on your store. The second email that sent the files as a .zip is most likely from Shopify’s Digital Downloads app. If you review the order timeline for this test order in your admin you should be able to see what app is sending the files once the order is complete. Our authenticated chat support team can also help you review this order if you need help finding out what app(s) might be sending digital files.