How do I fix "RemoteEvent is not a valid member of ReplicatedStorage" error message?

I have a script that teleports players at the start of a game and has messages that show up on a TextLabel. For some reason it is not working, so I looked at the warnings and error messages. The error message says "RemoteEvent is not a valid member of ReplicatedStorage", and there are warnings that say "Unknown global 'player'". There are blue underlines under where it says player in the remote.FireClient spot. I appreciate any help. Thanks!

EDIT: I have fixed the "RemoteEvent is not a valid member of ReplicatedStorage" error and the "Unknown global 'player'" warnings, but now it says "FireClient: player argument must be a Player object". I don't know why it says this as I believe am using a Player object, as shown below in my code. Thanks for helping, and sorry for the beginner questions.

Script code:

local oldMessage = ""
local minPlayers = 1
local Players = game:GetService("Players")
local player = Players.LocalPlayer

local messagePlayerEvent = Instance.new("RemoteEvent")
messagePlayerEvent.Parent = game.ReplicatedStorage
messagePlayerEvent.Name = "MessagePlayerEvent"

function teleportPlayers()
    local TeleportTarget = ""
    local target = CFrame.new(workspace.StartP1.Position)
    for i, player in ipairs(game.Players:GetChildren()) do
        TeleportTarget = (string.format("StartP%s", i))
        target = CFrame.new(workspace[TeleportTarget].Position)
        player.Character.HumanoidRootPart.CFrame = target
        player.Playing.Value = 1
    end
end

function message(message)
    if oldMessage ~= message then
        oldMessage = message
        print(message)
    end
end

function playersCurrentlyPlaying()
    for i, player in ipairs(game.Players:GetChildren()) do
        if player.Playing.Value == 1 then return true end
    end
    return false
end

game:GetService('Players').PlayerAdded:Connect(function(player)
    player.CharacterAdded:Connect(function(character)
        character:WaitForChild("Humanoid").Died:Connect(function()
            player.Playing.Value = 0
        end)
    end)

    local playing = Instance.new("IntValue", player)
    playing.Value = 0
    playing.Name = "Playing"
end)
while(true) do
wait(10)
    if #game.Players:getPlayers() >= minPlayers then
        if playersCurrentlyPlaying() then
            local text = "Waiting for an available arena..."
            messagePlayerEvent:FireClient(player, text)
        else
            local text = "There are enough players for a new game!  Teleporting..."
            messagePlayerEvent:FireClient(player, text)
        wait(4)
            teleportPlayers()
        end
    else
        local text = "Waiting for more players..."
        messagePlayerEvent:FireClient(player, text)
    end
end

LocalScript code:

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local messagePlayerEvent = ReplicatedStorage:WaitForChild("MessagePlayerEvent")

messagePlayerEvent.OnClientEvent:Connect(function(text)
    script.Parent.Text = text
end)