padlock System in Roblox Studio

local door = workspace.FirstBox
local GroupId = -- your group id
local MinRank = -- min rank the player needs

game.Players.PlayerAdded:Connect(function(player)
    player.Chatted:Connect(function(msg)
        if player:GetRankInGroup(GroupId) >= MinRank then
        for i,v in pairs(door:GetChildren()) do
            if string.sub(msg,1,6) == "/lock1" and v:IsA("Part") then
                v.CanCollide = true
                v.Transparency = .8
            elseif string.sub(msg,1,8) == "/unlock1" and v:IsA("Part") then
                v.CanCollide = false
                v.Transparency = 1
            end
        end
    end
    end)
end)