I can't launch the game in the browser (Safari)

[Caffa]

It says that startup.txt cannot be located but the file is in the folder.

[Flurrywinde]

It sounds like you might be running the game locally on your own computer. If so, choicescript has trouble with most browsers when run locally. Try firefox. If that doesn't work, try running the game through this: https://www.mamp.info/en/

If neither of these work, please provide more information about what's going on. Are you running this on your own computer? Which game? How did you install it? Etc.