Having Trouble with ':GetChildren()' In my mains script for my game. Can you guys solve it?

Hello,

Recently I was trying to script a sword fighting game. Im not good at scripting, and had many errors. I am having trouble with ":GetChildren()" In 1 part of my code. Ive watched many tutorials to help me, but still can't find the problem.

(Script)(I put words where the script is: local AvailableSpawnPoints = SpawnPoints)

-- Define Values

local ReplicatedStorage = game:GetService("ReplicatedStorage")

local ServerStorage = game:GetService("ServerStorage")

local MapsFolder = ServerStorage:WaitForChild("Maps")

local Status = ReplicatedStorage:WaitForChild("Status")

local GameLength = 100

-- Game loop

while true do

Status.Value = "Waiting for more players"

repeat wait(1) until game.Players.NumPlayers >= 2

Status.Value = "Intermission..."

wait (10)

local plrs = {}

for i, player in pairs(game.Players:GetPlayers())do
    if player then
        table.insert(plrs,player)-- Add each player into plrs table
    end
end

wait (2)

local AvailableMaps = MapsFolder:GetChildren()

local ChosenMap = AvailableMaps[math.random(1,#AvailableMaps)]

Status.Value = ChosenMap.Name.." Chosen"

local ClonedMap = ChosenMap:Clone()
ClonedMap.Parent = workspace

--Teleport Players to map

local SpawnPoints = ClonedMap:FindFirstChild("SpawnPoints")

if not SpawnPoints then
    print("SpawnPoints not found!")
end

local AvailableSpawnPoints = SpawnPoints 

for i, player in pairs(plrs) do
    if player then 
        character = player.Character

        if character then
            --Teleport them

            character:FindFirstChild("HumanoidRootPart").CFrame = AvailableSpawnPoints[1].CFrame
            table.remove(AvailableSpawnPoints,1)

            --Give them a sword

            local Sword = ServerStorage.Sword:Clone()
            Sword.Parent = player.Backpack

            local GameTag = Instance.new("BoolValue")
            GameTag.Name = "GameTag"
            GameTag.Parent = player.Character

        else
            --there is no character
            if not player then 
                table.remove(plrs,i)
            end 
        end
    end     
end


Status.Value = "Ready... Go!"

wait(2)

for i = GameLength,0,-1 do

    for x, player in pairs(plrs) do     
        if player then

            character = player.Character

            if not character then               
                --Left the game                             
            else                            
                if character:FindFirstChild("Gametag") then
                --They are still alive                      
                    print(player.Name.." is still in the game")                     
                else
                --they are dead                         
                    table.remove(plrs,x)                        
                    print(player.Name.." has been removed")                                         
                end                 
            end                 
        end 
    end     
    Status.Value = "There are "..i.." seconds remaning / "..#plrs.." players left"

    if #plrs == 1 then  
        --winner                        
        Status.Value = "And the winner is..."..plrs[1].Name 
        break                       
    elseif #plrs == 0 then              
        Status.Value = "Nobody won :/"              
        break               
    elseif i == 0 then                  
        Status.Value = "Time ran out :/"                    
        break                   
    end

    wait(1)
end

print("End of game")    

wait(2)


for i, player in pairs(game.Players:GetPlayers()) do    
    character = player.Character

    if not character then
    --ignore        
    else    
        if character:FindFirstChild("Gametag") then 
            character.GameTag:Destroy()     
        end         
        if player:FindFirstChild("Sword") then  
            player.Backpack.Sword:Destroy()             
        end

        if character:FindFirstChild("Sword") then       
            character.Sword:Destroy()       
        end

    end

    player:LoadCharacter()  
end

ClonedMap:Destroy() 

Status.Value = "Game ended"
wait(2) 

end