I bought a Europe bo4 key for battlenet because its cheaper without realizing it was eu only. I am from Europe so i activated it, would i be able to use this copy of the game to play with someone in Canada who has the version of the game for their region and play dlc zombies maps with them?
If you’re playing on PC, yes. While the key is region specific once claimed the key should allow you access to the Americas region as well, you simply change your region above the Play button.