In order for you to play Prison Architect on Linux with minimal graphics settings, your computer must meet the following requirements
Operating System:
Ubuntu 18 or later
Processor (CPU):
Intel Core2 Duo 2.4Ghz or Higher / AMD 3Ghz or Higher
Memory (RAM):
6 GB RAM
Graphics Card:
Nvidia 8600 / Radeon equivalent (2009 era)
Hard Drive:
500 MB HD space