How do I get player information as in inventory? If i can

MarketPlaceService - As of the Service that handles player assets, I would assume there isn't a function. Unless, you want to create a variable for every Hat ID there is in a table and check if the player owns that hat, but that's pretty much a mess and memory consuming, as there are plenty of hats.

Example:

local marketPlaceService = game:GetService("MarketplaceService")

local possibleHats = {"Hat1_ID","Hat2_ID","Hat3_ID","And So On"}

game.Players.PlayerAdded:Connect(function(player)
    for _,hat in pairs(possibleHats) do
        if marketPlaceService:PlayerOwnsAsset(hat) then
            local hatsValue = player:WaitForChild("leaderstats"):FindFirstChild("Hats")
            hatsValue.Value = hatsValue + 1
            print("Player Owns Hat")
        end
    end
end)

Hope this gave you an understanding of why this is a hassle and why you wouldn't be able to do this so easily.

~killerbrenden