You are supposed to be looking inside this project and understanding how this works so you can copy it and use it in games. If you encounter any bugs please adress them in the comments. There is a limit to how much a cloud variable can store can store so you might have to get creative if 1000 people use your project. Also if a person's name is long it will take up more save data space so my estimation might be off by a lot.
100% me if you are to use this engine credit me suggested games to use this in: RPGs puzzle games (if it has many levels) trading card games (these will probably have more achievements so it might fill up faster) long platformers #tutorials