From what I can tell, that sign was an error that may have been misinterpreted from the ad, as that week, buying an Xbox would make you eligible for a free game between $19.99 and $79.99. Devil May Cry 5 was pictured for the promotion (as well as I believe The Division 2?). Most likely, whoever made the sign misunderstood and had the wrong information. Had a physical copy been added to the purchase, then it would’ve been free. The ad mentioned this, but not the free digital game, which leads me to believe wires got crossed somewhere. Hopefully the guys here can take care of this for you, but yea, I believe this was just misprinted signage (it happens from time to time and Best Buy often posts signs to make those errors known to customers).