If an Animator is a descendant of a Humanoid or AnimationController in a Player’s Character then animations started on that Player’s client will be replicated to the server and other clients.
If the Animator is not a descendant of a player character, its animations must be loaded and started on the server to replicate.
If the Animator is created on the server, loading an animation and playing it on the client should replicate. Everyone else will be able to see it as long as the Animator wasn’t created on the client.