They sell the 1600 card in two variants. A physical card they ship to you, or a digital code. Double check the item description when you buy it, it should say "Digital Code" or something on there. The code is generally processed fairly quick, but I've had times where it took up to two hours for a code to be sent to me.
The code is shown on screen, stored in your account for future reference if you need it, and I believe you get an e-mail confirmation which includes a link to the page in your account where the code is displayed.