In the Advanced Settings, turn off your PJ-SIP Channel Driver. That should get rid of the error. If it doesn’t, you can create the files using “touch /etc/asterisk/pjsip_wizard.conf” from the console.
It depends on whether you support PJ-SIP. On one of my installations, it’s all Chan-SIP. On the rest, I mix both. If you are using (or planning on using) PJ-SIP, the ‘touch’ command works fine.