Does Evil Dead: The Game have a campaign?
The answer to this question is "sort of". It doesn't have a wholly unique singleplayer campaign on launch but it does have a singleplayer mode. There are a handful of small singleplayer only sections and the entirety of the game can be played alongside bots. In this sense, the game itself is kind of a campaign.
It does have a story of sorts and will take you through the eyes of four survivors. It is essentially an intentional recontextualising of the multiplayer maps, strung together to make one complete package. You won't notice intentional detail put in to establish a campaign but you can play it in a run.
The fact that the team have put in singleplayer exclusive maps does show the potential for a full-on singleplayer campaign but we won't have this on launch. Hopefully, if the game is successful, we may get a little more here in the future.
Does Evil Dead: The Game have Crossplay?
Yes, Evil Dead: The Game will have crossplay from launch. It will be fully compatible with console and PC players, allowing you to bring some buddies and take out the competition
It is unsure if this is toggleable just yet but it seems likely it will be. These kinds of multiplayer games tend to let players have a choice - mostly because there are some differences between PC and console players it has to account for. Keyboard and Mouse tend to allow a wider range of accuracy and PCs are a little easier to deploy cheats on. This being said, it's worth playing with that player base anyway.