If you're trying to play NBA 2K16 but are receiving a message with the error codes "EFEAB30C" or "4B538E50", a common reason for seeing these errors is because you don't have the latest data downloaded. When that happens, it means you can't continue on to play until you've got the most recent update downloaded.
If that's the case, please select the Play Now option and remain on the menu until you see a pop-up message asking you to return to the game's main menu so the update can go into effect. Exactly how long this takes varies, depending on the size of the download and the speed of your internet connection.
That said: Once it's completed you should be able to play without a problem.