Does this API automatically start training the voice?

API uploads are automatically processed.

Voice creation API

API uploads are automatically processed for the most part.
Our system will first check the provided audio consent file.
If there are no issues caught, then someone on our team will manually approve the voice building.
Once that's kicked off, our system will automatically process and segment the input data.

As long as there are no data issues, the remainder of the voice creation process is automated.