This Collector's Edition contains the 3 DLCs "Relic Rune Pack", "Character Skin: Dark Dracula" and "Character Skin: Armoured Dracula" and here's where you can find them in-game:
Relic Rune Pack:
Once you’ve redeemed the code, start playing the game as normal. This ability will become available once you have picked up your first relic!
Select 'Game Options' from the 'Configuration' menu in-game after you’ve redeemed the code to access this DLC.
After redeeming the code, you will be able to select this DLC by choosing 'Additional Content' from the Main Menu in-game.