Their paper says that they trained it on the Lakh MIDI dataset, and they have a section on potential copyright issues as a result.
Assuming you don't care for legal issues, theoretically you could do:
raw signal -> something like Spotify Basic Pitch (outputs MIDI) -> Anticipatory (outputs composition) -> Logic Pro/Ableton/etc + Native Instruments plugin suite for full song
Text to audio is too limiting. I’d rather input a melody or a drum beat and have the AI compose around it.