Marketpress downloadable file error

My client is distressed because her customers can't download their purchases.
What we've done is made four gift certificate images as variations of a product that must be downloaded and redeemed in store. But the site is not producing the image download successfully. They've had to pick them up in store which defeats the convenience of online purchase. She has confirmed in her Stripe account that the payments do go through. She tried to purchase one herself and got the same error, but the status of her purchase is "shipped".

Here is the email sent by the site:
"Your order is now available to download! Please refer to your Order ID (1c1bc4c04cf1) whenever contacting us.

Here is a confirmation of your order details:

Order Information:
Item Sku Qty Price Total
Gift Certificate Purchase: $50
( )
— 1 $50.00 $50.00
Order Total: $50.00"

When I go here it says order received - with download link that says error.
( )

Please help me resolve this! She's had such a hard time with Marketpress, I don't blame her for being distressed. I will give you access, let's figure it out.