How do i make a player receive a knife from the catalog, after clicking a part?

i have a part with a script and a click detector so whenever someone clicks it they can purchase my tshirt. But i want to make it where when they clcik the part and purchase my tshirt, i want them to receive a knife bundle that i made inside there assassin inventory. sorta like when they purchase VIP and the game gives them a kinfe and effect.

what script do i use to make it happen?

yes, i already have a part with a script and click detector.

heres what i want them to receive after they purchase my tshirt: https://www.roblox.com/catalog/846792499/Blue-Laser-Scythe

https://www.roblox.com/catalog/4879823654/Blue-Scythe

I believe you can paste this code into the command bar, and load the gear into your game. Then you can handle the cloning to the player's backpack.

game:GetService("InsertService"):LoadAsset(ASSET ID).Parent = game.Workspace

You might even be able to use this code to load the asset into the backpack, but I would recommend just making a folder of tools and using :Clone(). I also recommend using a gamepass, not a T-Shirt.

If you don't already have a script to check if they own the shirt, try using this: https://developer.roblox.com/en-us/api-reference/event/MarketplaceService/PromptPurchaseFinished

EDIT: You actually can use Insert Service to load the asset. As I said, I would recommend just inserting it to the workspace, but here's an example on how you could load the Laser Scythe.

game.Players.PlayerAdded:Connect(function(plr)
	game:GetService("InsertService"):LoadAsset(846792499).LaserScythe.Parent = plr:WaitForChild("Backpack")
end)