To make a successful client-to-server RPC (execute on server node) happen it must be called from within the blueprint of a class that is part of the connection-owning hierarchy, such as a playercontroller.
Doing it from a blueprint that is not will unfortunately silently fail.
So usually I will have playercontroller get the Game state and use that to call the event on Server. So it runs on the server’s gamestate and from there it finds the door actor and tells it to move.
The trick is going to be finding the door actor from within the gamestate to tell the door to either multicast or set repnotify the door open boolean variable (either of those methods will cause the change on all clients).
This is where it comes in handy to set Tags on your actors placed in the level because then the server rpc event can do a GetAllActorsWithTag using a string or Name fed into it from the event node (you can add parameter variables to those to send information through) and just Get index 0 from the array that GetAllActorsWithTag node returns.
As for telling your timeline to play AGAIN every frame, 60 times a second, I think there are better ways but the networking is the tricky part so I focused my answer on that.