Use a remote event to fire information from the server to the clients. Then, when it is fired, make a local script detect that and show the screen. Make sure to use :FireAllClients.
local RepStorage = game:GetService("ReplicatedStorage")
local RemoteEvent = RepStorage:WaitForChild("RemoteEvent") -- add Your Event here
local ClickDetector = --- Get the ClickDetctor
Since you are a rookie I would recommend learning how remote events work on youtube as it is extremely crucial for this. What ABHI said is correct you gotta use a remote event, and (remote event here that is pre-defined):FireAllClients(info here) to the local scripts. FireAllClients just basically means that it is sent to all the clients(players).