Obsidian has a feature called "Shared vaults" which teams use to collaborate. You can also use a shared Git repo, or other cloud/network storage (e.g. Dropbox)
I used it with a team of 10 folks at my previous job. Everyone worked in a common git repo, and with some smart usage of .gitignore, we were all able to collaborate quite effortlessly, even going so far as to push videos, images, etc to the repo with git-lfs to make the documentation rich and available. It can certainly be multiplayer with a modicum of effort.
https://help.obsidian.md/Obsidian+Sync/Share+remote+vaults