In terms of blueprints calling would be connecting node in a line for execution. In your case the blue multicast and blue RPC nodes are being called.
On the graph above RPC is not reaching cliens since it’s being called only on owner. I assume you are testing with “dedicated” flag off and when you are rotating character in server window it replicates, but in client window it is not.
What you should do:
In your Character class get player controller, get your rotator from player controller.
Then add multicast function which will set your charactets rotation (all in Character) and call it in tick of your character, passing rotator that you got from player controller.