Guided Access is a great iPad feature that will ask you to create a code upon locking your iPad to our app. This ensures that your visitors can't close the app or otherwise access anything on your iPad.
To activate, open the settings on your iPad and select General > Accessibility, then scroll down to Guided Access:
Make sure to toggle Guided Access on, as well as the Mirror Display Auto-Lock option at the bottom. Tap Passcode Settings, then tap Set Guided Access Passcode. Enter a passcode, then reenter it.
Once those are activated, select the Display & Brightness area on the left hand menu, and ensure Auto-Lock is set to Never:
Once these settings are all complete, open The Receptionist app and triple-click the Home button to begin your Guided Access session.