On the off chance the you get to download the DLC from Uplay, Steam still wont recognize that. Now when steam starts looking, it doesnt find any Steam compatible product activations on your game(refer to paragraph 2). About the expansion, Uplay knows you have the expansion, but you own the game on Steam so you would have to download the files from Steam(refer to paragraph 3).

Some of the stuff like weapons and outfits are already in the game files(because they drop from the heka chest) so you get them without hassle.

You put in your key in Uplay and it accepts the key. If you play steam games, you need steam files. But if its from Steam you would have to download from steam nontheless( again, not a uplay issue. It would accept any keys for any Ubisoft products. Uplay and Steam are completely compatible with each other, but Steam being primarily a distribution platform, it WONT support products that it doesnt get a cut from. Seems like most people dont quite understand how multi DRM compatibility works.

Ac valhalla season pass download