Hi there,
This can be done in a couple of different ways. It depends on what part of your site you’re referring to.
The first way is the single download page itself. When you created a new Download entry from your WordPress dashboard, that entry got its own front-end page. And if that’s what you’re referring to, the way the content is structured depends 100% on your theme. Most themes will show the name, description, and purchase link automatically. The thumbnail is not always guaranteed as its important that the theme supports the display of featured images.
The other way this content is shown is from the [downloads] shortcode. https://docs.easydigitaldownloads.com/article/224-downloads There are parameters available in that shortcode that control how the product presentation is structure. You can use the [downloads] shortcode in your content on page post or page and control the display of this information.
Note: Make sure you always use the Featured Image setting to upload a thumbnail for your ebook. Placing an image directly in the content will not display the same in either approaches I mentioned above.