Hi Delia
I have installed your plugin to my 1.5.1 development environment and have it working at least part of the way. It is worth pointing out, I am not a Zen Guru or PHP expert.
I can see the four fields when I add a product and I can see the content of those fields in your SQL table alongside the product ID I copied from the Zen Products table. So far, so good!
When I preview the product I can see Text which says files to download, and below that I see (in blue text) the title of
the file I entered in the field. However, if I click the blue text I get an error as shown here and when I view the page as a user I see this and this is what I can see in your SQL table
The product 'Seared Halibut' is created as a 'Product_general' class rather than a new class as previously suggested by another user.
I have edited my custom tpl_product_info.php as mentioned elsewhere on your site but still nothing shows in the user view also I have edited the downloads and product_extra_files folders to 777 for test purposes.
I hope you are able to understand my issue.
Many thanks in advance,
Bob