The expo-detox-hook is an iOS framework that you install via npm, and it gets put in your Library directory. This package exists because we need to call into the test runtime and add some extra changes in order to get Detox and Expo platforms to play well with each other.
You can install the framework by declaring expo-detox-hook in your package.json and running npm install, which should install the framework to your Library directory.
Unless you get an error, you shouldn't need to do anything else here.