i understand that digistore requires the customer to be signed in to make a purchase, but when they are not, and have added items to their cart, and press the checkout button, there is an error dialog that pops up:
Unable to retrieve session data.
This is confusing to customers or potential customers that could be reminded to login and/or register at this point.
It looks like a bug. Actually if you click on checkout you will see this: "Register or login to checkout".
Submit a support ticket and we will help you with this.
Best regards,