Why am I getting HTTP 403(Forbidden) in Output when teleporting players?

Hi, I hope you could help me with a problem. I am making a game and i am making a lobby to teleport you and when the timer runs out it is meant to teleport the players that are ready. But, in my output it says:

 14:43:08.772 - HTTP 403 (Forbidden)
14:43:08.775 - Stack Begin
14:43:08.775 - Script 'Workspace.Gate.TouchGateScript', Line 41 - function teleportPlayers
14:43:08.776 - Script 'Workspace.Gate.TouchGateScript', Line 100
14:43:08.776 - Stack End

When i click the error line, it takes me to this script line in one of my scripts:

local code = TS:ReserveServer(placeId)

Here is the script that handles the teleporting:

local TS = game:GetService("TeleportService")
local TweenService = game:GetService("TweenService")
local placeId = "5175452059"
local leaveGuiEvent = game.ReplicatedStorage.LeaveGuiEvent
local TransitionEvent = game.ReplicatedStorage.TransitionEvent
local list = {}
local gui = script.Parent.GuiPart.SurfaceGui
local billboard = script.Parent.billboardPart.billboardGui
local timer
local teleporting = false
local spawnTeleport = script.Parent.spawn

local function updateGui()
    gui.Frame.players.Text = #list
    billboard.Frame.players.Text = #list
end

local function removeFromList(character)
    for i=1,#list do
        if list[i] == character.Name then
            table.remove(list,i)
            updateGui()
        end
    end
end

local function teleportPlayers()
    if #list > 0 then
        script.Parent.GuiPart.SurfaceGui.Frame.Status.Text = "TELEPORTING"
        script.Parent.GuiPart.SurfaceGui.Frame.Status.TextColor3 = Color3.new(1,0,0)
        local playersToTeleport = {}
        local teleportTime = 0
        for i=1,#list do
            if game.Players:findFirstChild(list[i]) then
                table.insert(playersToTeleport,game.Players:findFirstChild(list[i]))
                TransitionEvent:FireClient(game.Players:findFirstChild(list[i]))
            else
                table.remove(list,i)    
            end
        end 
        local code = TS:ReserveServer(placeId)
        teleporting = true
        TS:TeleportToPrivateServer(placeId,code,playersToTeleport)
        repeat wait() until #list <= 0
        script.Parent.GuiPart.SurfaceGui.Frame.Status.Text = "READY"
        script.Parent.GuiPart.SurfaceGui.Frame.Status.TextColor3 = Color3.new(34/255,255/255,20/255)
        teleporting = false
    end
end

script.Parent.Gate.Touched:Connect(function(hit)
    if hit.Parent:findFirstChild("Humanoid") then
        if teleporting == false then
            local char = hit.Parent
            local player = game.Players:FindFirstChild(char.Name)
            local alreadyExists = false

            for i=1,#list do
                if list[i] == char.Name then
                    alreadyExists = true
                end
            end

            if alreadyExists == false then
                if #list < 16 then
                    table.insert(list,char.Name)
                    char.PrimaryPart.CFrame = spawnTeleport.CFrame
                    updateGui()
                    leaveGuiEvent:FireClient(player)
                end

                player.CharacterRemoving:connect(function(character)
                    removeFromList(character)
                end)
            end

        end
    end
end)

leaveGuiEvent.OnServerEvent:Connect(function(player)
    if player.Character then
        player.Character.HumanoidRootPart.Anchored = false
        wait()
        player.Character.Humanoid.Jump = true
        wait()
        removeFromList(player.Character)
        player.Character.Humanoid.Health = 0
    end
end)

while wait() do
    timer = 30
    for i=1,timer do
        timer = timer - 1
        gui.Frame.time.Text = timer
        billboard.Frame.time.Text = timer
        wait(1)
    end
    teleportPlayers()
end

Could you help me with this? I have enabled HTTP Requests and Studio Access to API but it makes no difference. I tested it on Studio AND Roblox but it gives me the same thing. Thanks.