How can we automatically add a marketing piece to every web order?

I created a simple product at no cost for this marketing piece and noticed that there is the functionality to enable the below but its not working when I test this out with just adding a couple of product ID's or category ID's. What am I missing? Is there a tutorial out there?
Thank you!

Require other products  
Required product IDs  
Automatically add these products to the cart

Is a marketing piece like an advertisement or coupon?  If you want it added to every single order, why not attach a PDF version of the marketing piece to something like the "OrderPaid.CustomerNotification" email message template?

Admin > Content Management > Message Templates > (find your email template) > (Advanced Settings) Attached static file

Or if a marketing piece is like a keychain or stickers, we just throw them in every box.  No sense accounting for them if they're free.

Thank you for your reply. It is a full-color catalog that we have to keep track of in terms of inventory as its also given to our B2B customers so its a bit more substantial than a coupon and not a giveaway like a gift.

Check that the marketing piece product
- is Published
- if using inventory control that it has stock