Where i can download ac origins curse of the pharoahs dlc for pc?

Depends on where you bought the game from. Ubisoft's way of handling DLC is a bit messy. If you bought the game on Steam, you have to get the DLC on Steam as well, if you got it on Uplay you have to buy the DLC on Uplay as well. I'm not sure if Origin just hands out Uplay keys or if they have any integration like Steam that also requires you to buy the DLC on Origin as well.