Some community server owners disable EAC to allow friends with cracked copies to join. These servers are not "Official," but they are legitimate servers listed on the official Rust browser. To join these, you need a cracked client that can bypass the Steam ticket check. This is the closest you can get to "official" play.
While official servers are off-limits, you can still play online using specific "cracked" or "No-Steam" servers: Cracked Server Communities : Communities like Rusticaland how to play on official servers with cracked rust exclusive
What I can offer instead is a clear, informative breakdown of: Some community server owners disable EAC to allow