If you’re looking for the easter egg in koala from 2022, it has already been made into a fully fledged feature and there is no need to unlock anything.
The easter egg was “Split Stems” which lets you separate a sample into different parts (e.g. drums, bass, vocals and other) – this feature DOES NOT work on Mac or windows, it’s an iOS/Android only feature – you can run the iOS version of koala on Mac to use it, but not the Mac version on the Mac app store.