D-Link DIR-868L User Manual page 46

Section 4 - Security
PIN: Select this option to use PIN method. In order to use this method you
must know the wireless client's 8 digit PIN and click Connect.
PBC: Select this option to use PBC (Push Button) method to add a wireless
client. Click Connect.
Once you click Connect, you will have a 120 second time limit to apply the
settings to your wireless client(s) and successfully establish a connection.
D-Link DIR-868L User Manual 42