The Adweek source linked goes into a little more about it, but not much. Specifically mentioning a model was used for lyrics first, then the AI created a melodic and percussive arrangement. It doesn't say much more about how it was done.

I found another article that states they had a real human voice sing the lyrics (then auto-tuned it to Scott's style), but there's no actual sources here, or on any other articles I can find.

https://musebycl.io/digital-data/agency-used-ai-make-travis-...