Muhammed432
Plutonium does not provide the coop/survival/coop mode, only the multiplayer mode.
You can do one of these:
Play it on Steam (unsure about online being secure, probably fine in a private game with a friend you can trust)
Find another client that supports it
(for survival mode only) Use Plutonium and load a mod that tries to recreate a similar experience to the survival mode experience such as this one or this one (seems to be US servers only, no download provided)
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