WhosOnLocation uses a plugin called MeadCo ScriptX to automate the printing of passes from any device printing using Internet Explorer.
WhosOnLocation licenses the MeadCo ScriptX plugin on an annual basis. Each time the license renews, you'll need to approve advanced printing. If you don't allow this, printing passes on a Windows device using Internet Explorer won't work.
On the message, click Yes, allow and you'll be able to print.