Oh I have misunderstood! I did not read your errors correctly and presumed they were part of an earlier issue. The problem is that the project uses very new techniques introduced in stable 2022.11. The "string" function explicitly now allows extra functionality that this project uses. I will add clarifications on this to the project page. Very sorry for not reading this properly! =(
And if either of you are unable/unwilling to update your GameMaker version for whatever reasons and therefore cannot use this project, please feel free to initiate a refund request with itch.io. Sorry about that!