I just ran a quick test and everything looks fine, I will double check anyway.

Few thinks to check, this plugin is set to sell shippable and digital products. To allow the users to download the images you need to create downloadable image sizes in your price list.

Set your sizes to px(pixes) and once you drag them to the price list check the checkbox next to the size name to make the size downlaodable.

if you are messing the file extension, check your files make sure that they also have file extensions.

To send email receipt make sure that you have the “Email receipt” checked in the settings > checkout, and remember that it will be email to the customer’s email saved paypal.