What does ’Some items in your order are not downloadable so will be processed manually’ in Linklok mean

The message  Some items in your order are not downloadable so will be processed manually means that Linklok didn't recognise one or more of the products ordered. In this case it assumes that these products are tangible items to be shipped manually. If the item should be downloadable then check that the ID field in your buy button matches the product id in Linklok. So for example if the ID is id1 then the product id in Linklok should also be id1