Email a Digital File After Physical Purchase?

Do you know which automation this would be? I explored this yesterday but found nothing labeled, “Send email after purchase.” Typing “email” or “PDF” renders no result in the search option.

I just created this one below but 1) it doesn’t tell me if it’ll populate after they make a purchase, only that it’s sent after an invoice is paid. But “WHAT” invoice? 2) there’s no option to assign it to a specific product nor attach a file. 3) they should not have to fill out ANY additional forms as they would make for a bad UX.