You can add products from the Website Editor and build your catalog inside the store editor.
Then go to All Products → Add New Product and complete the General details (name, description, category, media, pricing, and more). You can also add a Ribbon (e.g., New / Best Seller / Sale) and enable Digital File for downloadable items.
Tip: When you add a new product, the previous product’s image may appear as a placeholder—remove it using the X icon and upload the correct image.