May have already been stated, but…
When picking up a pre-ordered physical copy of MK11 from a retail location, be sure (1) you get a physical receipt and (2) that the Shao Kahn DLC code is printed on that receipt.
Picked up my game at Best Buy this morning, accepted an email receipt in lieu of a physical receipt – turns out the email receipts don’t include DLC codes. If a receipt is physically printed after the item has been picked up, it will be a “duplicate” receipt which won’t have any codes on it (as a default precaution). BB employee had to transfer my call to their Download Center – they verified my purchase & contact info, and are emailing my code to me (but that might take 24-48 hours).
So, just a word of caution if you’re picking up a pre-ordered physical copy of MK11 later on.