Add Discord user

Hello dear team, I would be happy if it would be possible to add/remove a user on a server by a trigger (purchase). I sell Discord Premium memberships. The people who get this membership get access to a certain area on the server. At the moment I have to check all orders manually and add the user manually. It would be great if the user enters their username at checkout and they are automatically added / invited with a unique link. I don't know if this is possible in principle but I would be happy if you could give me an update.