The Praim B91-VDI thin client model is based on Raspberry Pi 3 Model B+ hardware.
Agile4PI software can be installed on both Raspberry Pi 3 Model B+ or Raspberry Pi 3 B hardware. Other Raspberry models are too slow to support the Agile environment in terms of speed and fluent user interaction. See also this link: Agile - O.S. & Software Compatibility.
Raspberry Pi 4
Be aware that Raspberry Pi 4 is not supported.