In the comments we find // The GPIO pins controlled by the FPGA start from 100
// Ok, so we know now that the FPGA contains the extended GPIO IP
// The GPIO pins controlled by the FPGA start from 100
// Please refer to the online documentation for the actual pin assignment
So why is the code then accessing the pins with numbers below 100?
// Let's configure pin A0 to be an output, controlled by the FPGA
FPGA.pinMode(33, OUTPUT);
FPGA.digitalWrite(33, HIGH);