Have you [contacted the Google Cloud sales team to request access](https://cloud.google.com/contact) to the allow list? 404 error for voices:generateVoiceCloningKey means your project isn't on the allow list for the restricted Instant Custom Voice feature. [Due to safety considerations](https://cloud.google.com/text-to-speech/docs/chirp3-instant-custom-voice#:~:text=Due%20to%20safety%20considerations%2C%20access%20to%20this%20voice%20cloning%20capability%20is%20restricted%20to%20allow%2Dlisted%20users.%20To%20access%20this%20feature%2C%20contact%20a%20member%20of%20the%20sales%20team%20to%20be%20added%20to%20the%20allow%20list.) , access to this feature is limited. Your logs support this, as other Text-to-Speech functions work.