I followed the instructions on how to setup Google Cloud Text-To-Speech and discovered a problem: The last step is to get an authorization code, for that you have to login into your google account and then google should give you the necessary code. However it says that OpenHAB is blocked by Google because the review is not completed:
Note, this is your openHAB application. It’s nothing that we have control over. All of those steps you’ve gone through are between you and Google. openHAB does not act as a go between.
You’ll have to wait for Google to approve your application.
To put it another way, everyone who uses Google TTS with OH is doing so individually and independently. There isn’t one openHAB integration, there is one integration per user.