My Building System Rotation is not working?

So, I was building a game where it would be crucial to build. I found a script in a video and tried adapting it to my needs. So far I have made it be able to place, but I can't make it rotate. Whenever I click r(Rotate) it twitches and then comes back to it's original rotation. Sometimes it works but not really. I want it to rotate by 45º for now. Like I said, I found this in a video and don't really understand what is happening in this script. If anybody can do a little extra and explain how to make the virtual placing grid 1 stud by 1 stud.

Thanks!

And also, here is the script:

local Mouse = game.Players.LocalPlayer:GetMouse()
local Visual = workspace.TestModel
local Hitbox = Visual.Hitbox


--[[function RoundByThree(Number) // Original
    if math.floor(Number) == Number then
        if Number%3 == 0 then
            return Number
        elseif (Number - 1)%3 == 0 then
            return Number- 1
        elseif (Number + 1)%3 == 0 then
            return Number+ 1
        end
    end
    return Number
end]]

function RoundByThree(Number)
    if math.floor(Number) == Number then
        if Number%3 == 0 then
            return Number
        elseif (Number - 1)%1 == 0 then
            return Number
        elseif (Number + 1)%1 == 0 then
            return Number
        end
    end
    return Number
end

Mouse.Button1Down:connect(function()
    local newBlock = Hitbox:Clone()
    newBlock.Name = 'Wall'
    newBlock.Parent = workspace
    newBlock.CanCollide = true
    newBlock.Transparency = 0
end)

Mouse.KeyDown:connect(function(key)
    key:lower()
    if key == 'r' then
        Hitbox.Orientation = Hitbox.Orientation + Vector3.new(0, 90, 0)
    end
end)

local LastPosition = CFrame.new()
while true do      
    if Mouse.Target then
        if Mouse.Target.Name == "Base" then
            local TycoonBase = Mouse.Target
            local TycoonBaseSizeX, TycoonBaseSizeZ
            local HitboxSizeX, HitboxSizeZ

            TycoonBaseSizeX, TycoonBaseSizeZ = TycoonBase.Size.x, TycoonBase.Size.z

            HitboxSizeX, HitboxSizeZ = Hitbox.Size.x, Hitbox.Size.z

            local TycoonTopLeft = TycoonBase.CFrame * CFrame.new(Vector3.new(TycoonBase.Size.x/2, 0, TycoonBase.Size.z/2))

            local RoundByThreeX = RoundByThree(math.floor(Mouse.Hit.p.x - TycoonTopLeft.x))
            local RoundByThreeZ = RoundByThree(math.floor(Mouse.Hit.p.z - TycoonTopLeft.z))

            if RoundByThreeX < -TycoonBaseSizeX + HitboxSizeX then
                RoundByThreeX = RoundByThreeX + HitboxSizeX
            end
            if RoundByThreeZ < -TycoonBaseSizeZ + HitboxSizeZ then
                RoundByThreeZ = RoundByThreeZ + HitboxSizeZ
            end
            local VectorComponent1 = CFrame.new(Vector3.new(TycoonTopLeft.x, Mouse.Target.Position.y, TycoonTopLeft.z))
            local VectorComponent2 = CFrame.new(Vector3.new(RoundByThreeX, Mouse.Target.Size.y/2, RoundByThreeZ))
            local VectorComponent3 = CFrame.new(Vector3.new(-HitboxSizeX/2, Hitbox.Size.y/2, -HitboxSizeZ/2))
            local NewVector = VectorComponent1*VectorComponent2*VectorComponent3
            local RegionVectorMin = NewVector * CFrame.new(Vector3.new(HitboxSizeX/2, -Hitbox.Size.y/2, HitboxSizeZ/2))
            local RegionVectorMax = NewVector * CFrame.new(-Vector3.new(HitboxSizeX / 2, -Hitbox.Size.y/2, HitboxSizeZ/2))
            local Hitboxes = game.Workspace:FindPartsInRegion3(
                Region3.new(
                    Vector3.new(
                        math.min(RegionVectorMin.x, RegionVectorMax.x),
                        math.min(RegionVectorMin.y, RegionVectorMax.y),
                        math.min(RegionVectorMin.z, RegionVectorMax.z)
                    ) + Vector3.new(0.1, 0, 0.1),
                    Vector3.new(
                        math.max(RegionVectorMin.x, RegionVectorMax.x),
                        math.max(RegionVectorMin.y, RegionVectorMax.y),
                        math.max(RegionVectorMin.z, RegionVectorMax.z)
                    ) - Vector3.new(0.1, 0, 0.1)
                ), nil, 100
            )

            local ModelColliding = false
            for i, Hitbox in pairs(Hitboxes) do
                if Hitbox.Name == "Hitbox" and not Hitbox:IsDescendantOf(Visual) then
                    ModelColliding = true
                end
            end

            if not ModelColliding then
                    LastPosition = NewVector
            end
            Visual:SetPrimaryPartCFrame(LastPosition)
        end
    end
    wait()
end