Hi Millenial Falcon,
This chart gives you a list of the serial interface names for different Arduino boards.
Arduino Uno has a single serial interface, called Serial(). It's the same serial interface used for USB - so if you're exchanging data over a USB serial connection, you can't simultaneously talk to the state machine. If you want to use Uno, change all references to Serial1() in your sketch to Serial().
For many applications, it can be very useful to have a USB connection in parallel with the link to the state machine. The following boards are compatible with the Arduino shield and allow for Serial1() in parallel with Serial() or SerialUSB():
Adafruit Metro M4
Arduino Due
These work too, but they're retired products so they may be harder to find:
Arduino M0
Arduino Zero
I'd caution that Arduino Uno has a 16MHz, 8-bit processor which may not be able to keep up reliably with Bpod's 1.3Mb/s serial bus speed (this speed is necessary to ensure reliable state machine transitions). On our product page, we recommend 32-bit Arduino boards like the ones I listed above, which all have much higher clock speeds. It's possible that Uno is fast enough to work - we just haven't tested it here. If you find that it works reliably, please let us know!
-Josh
