Module not requiring, help?

The script are yielding and the event connect after the player joins, then the event will not get fired, to fix that you need to do a generic for loop within all players that joined before the event fires, here is a example:

wait(2)

local Players = game:GetService('Players')

local function onPlayerAdded(player)
    print(player.Name, 'Joined!')
end

Players.PlayerAdded:Connect(onPlayerAdded)
for _, player in pairs(Players:GetPlayers()) do
    print(player.Name, 'is already in game, calling onPlayerAdded!')
    coroutine.wrap(onPlayerAdded)(player) -- start a new thread and call the function!
end

this will solve the problem

Fixed Code:

-- Services
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local ServerScriptService = game:GetService("ServerScriptService")
local Players = game:GetService("Players")

-- Modules
local ModuleScripts = ReplicatedStorage.Modules
local GameSettings = require(ModuleScripts.GameSettings)
local PlayerManagement = ServerScriptService.PlayerManagement
local PlayerManagementModules = PlayerManagement.ModuleScripts
local Data = ServerScriptService.Data
local DataStore = require(Data.Modules.DataStore)
local UpgradeManager = require(Data.Modules.UpgradeManager)

-- Local Functions
local function setupPlayerStats(player)
    local character = player.Character or player.CharacterAdded:wait()
    local humanoid = character:WaitForChild("Humanoid") 

    local LeaderStats = Instance.new("Folder",player)
    LeaderStats.Name = "leaderstats"

    local OtherStats = Instance.new("Folder",player)
    OtherStats.Name = "OtherStats"

    local Money = Instance.new("IntValue",LeaderStats)
    Money.Name = "Money"

    local Reborn = Instance.new("IntValue",LeaderStats)
    Reborn.Name = "Reborn"

    local Cropfarmed = Instance.new("IntValue",LeaderStats)
    Cropfarmed.Name = "Crop Farmed"

    local Vip = Instance.new("BoolValue",OtherStats)
    Vip.Name = "Vip"

    local Donator = Instance.new("BoolValue",OtherStats)
    Donator.Name = "Donator"

    local Tutorial = Instance.new("BoolValue",OtherStats)
    Tutorial.Name = "Tutorial"

    local Pets = Instance.new("Folder",OtherStats)
    Pets.Name = "Pets"

    local Wheat = Instance.new("IntValue",OtherStats)
    Wheat.Name = "Wheat"

    local Carrots = Instance.new("IntValue",OtherStats)
    Carrots.Name = "Carrots"

    local Potatoes = Instance.new("IntValue",OtherStats)
    Potatoes.Name = "Potatoes"

    local Multyplier = Instance.new("IntValue",OtherStats)
    Multyplier.Name = "Multyplier"

    print("work")

    UpgradeManager:Update(player)
end

Players.PlayerAdded:Connect(setupPlayerStats)
for _, player in pairs(Players:GetPlayers()) do
    coroutine.wrap(setupPlayerStats)(player)
end

Hope it helped! :)