It may help to make a few distinctions here.
The Thank-you Page is a Web page that buyers can access after their payment is completed. This is where we provide their download link(s), along with any text/HTML customizations you have added to the Thank-you Page fields in your Seller Admin. Product-based customizations get shown first on this page, followed by any Common customizations.
The Thank-you Email is a message we send to the buyer's email address after payment is completed for a digital (download) product; we don't normally send a separate thank-you email for tangible (physical, shippable) goods, unless you have entered something in that product's Email Message field. For digital goods, this message would normally include a link to reach the thank-you page, where buyers would claim their file download.
Let's suppose a buyer orders one digital item and one tangible item. Let's also suppose that the tangible product's settings have something entered in the Email Message field, and that the digital product at least doesn't have Enable Templated Email checked with the Email Message field left blank. The buyer would then receive two thank-you email messages -- one message for the digital item (with a link to reach their thank-you/download page), and another message for the tangible item. If you also happened to have a Common Thank-you Email Subject and Message configured (in Admin > Account Prefs), this would generate a third email message to the buyer, in addition to the two product-based emails.
If you want the buyer to receive just one Thank-you Email message for all products, regardless of which or how many products are ordered, you would leave each product's Email Message field blank and also Enable Templated Email for digital products. Then you would go into Seller Admin > Account Preferences and enter a Common Thank-you Email Subject and Message, Enable Templated Email, and compose your entire message with the [%thankyou_link%] code inserted wherever you want a link to the thank-you/download page to appear in your message. A basic Common Thank-you Email template might look like this:
Subject: Your [%business_name%] purchase
--
Dear [%first_name%],
Thanks for your purchase. Your can view your order details and obtain any downloads you purchased here:
[%thankyou_link%]
{add'l info/instructions/offers would go here}
Sincerely,
[%business_name%]
