Prior to the 22-23 competition season, the only microcontrollers used on the car were NERduinos, which use Teensy 4.1. While these are excellent microprocessors, they’re both difficult to acquire and fairly expensive ($40).
(ARM Cortex-M7 at 600 MHz, 7936K Flash, 1024K RAM), they’re both
If you want a really in-depth walk through of the entire Altium design cycle for an STM32 board, this video is an excellent resource: