If you need AT2 for a single weekend project, those trials are your solution. If you need it permanently, respect the developers and buy a used Korg Pa300 (under $400 used) or subscribe to Pa5X Mobile.
Because AT2 is backward compatible, you can load into free software that reads Korg formats. The software does the arranging, not the hardware. korg at2 free
AT2 is the engine that listens to what you play (chords, rhythm, dynamics) and instantly generates a professional backing band—bass, drums, guitars, strings, and brass—in real-time. If you need AT2 for a single weekend