Hi,
From what I can see, this would indicate that you're using the Starter edition. However, the download area and has always been for the commercial editions of HikaShop.
So I'm surprised you had it before the update ? Maybe there was a bug which didn't check properly the edition of your HikaShop.
Thank you for your feedback, I've added a patch on our end so that such error can't happen even in such case. However, I'm afraid that even with the patch, it won't allow you to access the download area with the Starter edition. Nevertheless, your customers already have access to their download if they open their order and in the email notifications.
If you have the error with other editions of HikaShop, then download again the install package on our website in the menu My account>My subscriptions and install it on your website again, and it will add the patch for that error.