Note: this board may have issues being prgrammed with QSTlink and by copying the bin file in USB drive mode. If this is the case, use st-flash
st-flash write ./main.bin 0x08000000
Thanks to Antonio Di Bello for the tip.
Reading printf output
The board default serial port is connected to the ST-Link, so the same USB cable used for powering and programming can be used for serial communication. Open a terminal and type screen /dev/ttyACM0 19200