AttributeError: module 'board' has no attribute 'D18' - Adafruit - Python

I'm trying to connect my BeagleBone Black with DHT11 sensor. I'm following the Adafruit guide they provide, but on script run:

import board
import adafruit_dht
import time
    stdin, stdout, stderr = bbb.exec_command('echo out > /sys/class/gpio/gpio45/direction')
    print("Connessione riuscita!!!!")
    # Sensor should be set to Adafruit_DHT.DHT11,
    # Adafruit_DHT.DHT22, or Adafruit_DHT.AM2302.
    dht_device = adafruit_dht.DHT11(board.D18)

    temperature = dht_device.temperature
    humidity = dht_device.humidity
    print(
    "Temp: {:.1f} , C Humidity: {}% ".format(
    temperature, humidity
    )
    )
    if humidity is not None and temperature is not None:
        print('Temp={0:0.1f}*C  Humidity={1:0.1f}%'.format(temperature, humidity))
    else:
        print('Failed to get reading. Try again!')
    # Fai suonare il buzzer per 10 secondi

It gives me the error: AttributeError: module 'board' has no attribute 'D18' . I also tried with the P8_11 pin which would be the actual one of the BeagleBone, but still it doesn't work.

Does anyone know how to fix this error, or alternatively give me a way to connect the two devices in Python? Thanks in advance.