Script dosen't work online why?

A server script does not have access to the variable LocalPlayer as the script is running on the server.

A local script does not have access the servers storage as it is only for the server to store objects in, if you need both the client and server to use the same objects then you can use ReplicatedStorage.

The reason why this works in solo mode is because you are both the server and the client meaning that both script types can access both server and client resources. It is best to also test by starting a server and not just relying on solo mode tests.

There is a lot which needs to be looked at as you have joined server script and local script functionality which will not work in a live server.

This is an example only, there may be syntax errors as I cannot run this to test.

local debounce = true -- ist best to start at true so you don't need to invert the boolean
local isActive = script.Parent.Parent.Job.JobActive

-- it is a good idea to get the services here
local servStorage = game:GetService('ServerStorage') -- 
local jobGui = servStorage:WaitForChild('CableMan'):Clone() -- stores a clone, alos use wait for child as we know we have the gui
local alreadyJob = servStorage:WaitForChild('ErrorGuis'):WaitForChild('AlreadyJob'):Clone() -- the wait for child stacks so wait fo errorgui then alreadyjob

function Shop(hit) 
    if debounce then
        if hit.Parent:FindFirstChild("Humanoid") then
        
			-- find the player form their character
			local plr = game.Players:GetPlayerFromCharacter(hit.Parent)
			
			if plr then -- if the player has been found e.g. game.Player.[plr name]
				debounce = false -- now that the player has been found set the denounce
				
				-- you could also check for the gui e.g. wait for child ect
				jobGui:Clone().Parent = plr.PlayerGui -- as we habe a clone we just make a cone of the clone and set the parent to the player gui
				
				if isActive.Value then -- as this is a boolean we dont need to check for a true you were doing true == true which is true and a waste of time
					-- the bit you had before		
					if script.Parent.Parent.CableMan then
	                	script.Parent.Parent.CableMan:Destroy()
					end
					
					-- we create a variable so we can destroy the gui after the wait time instead of looking for it again which is slow
					local tmpGui = alreadyJob:Clone()
					tmpGui.Parent = plr.PlayerGui
					
					wait(2)
					
					tmpGui:Destroy()
				end
				
			end		

            wait(10)
        	debounce = true
		end
	end
end

game.Workspace.Jobs.CableMan.Touched:connect(Shop)

I have changed a lot of the code to remove the localplayer dependencies, please comment if you do not understand why / how this code works. If you do not understand any of the methods I have used please first check the wiki page.

There are also other methods of doing this e.g. in a local script. But I do not know what method is best for you game.

Hope this help.