Since all the entries for this are already 4 months old and all are in English (and especially all before the update to Crossplay), I ask it briefly here. So I have already seen in the settings that there's inevitably the tick in Crossplay and you can't remove it. That means it has to be active, in addition to that I've played with people from time to time who didn't have a steam profile and besides their name, it was a strange world symbol. Well and good so far but how can I consciously use crossplay so I (PC) with my buddy (PS4)?
Crossplay is so far only possible for people who play the game on Steam or bought or bought elsewhere. This means that only PC players can still play together. But there will likely be a possibility soon that PC players and PS4 players can play together.
There's no real crossplay yet. The "crossplay", which is currently in the game, refers to the interaction between the Windows Store and Steam versions. Of course they are both for PC.
However, there seem to be rumors that the developers are trying to add proper console / PC crossplay. At least there were a few buggy lobbies where PC gamers could join console lobbies.