I know them, back when they started we traded some models, but not since they became large. And the "free sharing assets" they tell is quietly a lie. They are looking for people doing them popular arcade maps of Warcraft 3 in reality. Hopefully we will also get some assets ready next year, but yeah 1-2 additional 3D and/or 2D artist wouldn't hurt.
My team already working on Warcraft 1 and Warcraft 2 remake. Multiplayer is already playable on EU and NA server(need 1-2 patch to fix a few stuff and most of the models are placeholder yet). Also around 70% with Warcraft 1 campaign.
Just want to forewarn you: C&C is not Blizzard IP so there is a high chance they will remove your map from Battle.net if it contains copyright materials. Ofc you can finish the campaign, that part they can't harm.