How to move players arm with Remote Event?

I made a LocalScript which moves the players arm and a Remote Event which should make the arm move to other players too. But I don't know how to move it for other players. The LocalScript moves the Motor6D (Shoulder) via CFrame.

Server script:

game.ReplicatedStorage.ArmMovement.OnServerEvent:Connect(function(player)

    --Here is the problem. What script do I have to use to move the arm?

end)

I tried adding

Shoulder.C0 = Shoulder.C0 * * CFrame.Angles(math.rad(-90),0,0)

but it didn't work.