When using a Brother QL-810/820Wc (note the ending "c"), you may need to customize your printer's HTTP server settings to allow AirPrint connectivity to print visitor badges.

This involves logging into the printer's web administration interface after the printer has been added to your network, and turning off the IPP setting for "HTTPS(Port443)" as shown in the screenshot below.

If the settings are applied properly to the printer, when selecting the printer via the AirPrint option on the check-in kiosk should have a current printer address beginning with "ipp://" (not "ipps://"). 

Accessing the Printer's Web Settings Page

To access the configuration web page for the printer once it's available on your network: