Buying the DLC for steam main game (compatible?)

Quick one, don;t know if anyone's tried it or knows if its possible.

Is it possible to buy the DLC direct from here and somehow activate it with a steam version of the game (even if not steam itself).

Long overdue waiting for this officially via the store but wondering if I can buy it from here and it'll work ok

(then get it on my steam account later probably needing to buy a 2nd copy when it hits 80% off in 9 months or so....)

yes it works fine

oh cool, will just do that then