Currently creating server authorative player animations is not possible (or not easily possible) using the Animator instance.
Currently in my game I have a server sided animation handler for players which removes the animator instance server side when a character is loaded, and then I make animators for every player client sided and do manual animation replication. I then replicate these animations to clients manually, however a limitation of AnimationTrack instances is that you cannot Play an animation at a set TimePosition while also allowing for smooth fade in. This results in choppy looking animations or out of sync animations.
Being able to set a property on an animator to disable client > server replication for played animations would be incredibly useful to ensure exploited clients cannot play a phrone/crouch animation while still having the advantage of full mobility/visibility.