Kiosk mode and Autostart on iOS devices.

Because of iOS limitations kiosk mode and autostart are set up using system features

To limit user's access to system and apps other then Addreality Player and thus set up kiosk mode you should use Guided Access.

Setting up Guided Access

Go to Settings > General > Accessibility > Guided Access.
Turn on Guided Access.
Tap Passcode Settings, then tap Set Guided Access Passcode.
Set up a passcode. From here, you can also turn on Face ID or Touch ID as a way to end a Guided Access session.
Open Addreality Player, then triple-click the Home button. For iPhone X, triple-click the side button.
If you want parts of your screen to stop responding to touch, use one finger to circle those areas. You can move or resize the circle, or tap the X to remove it.
Tap Start.

Also Guided Access allows you to lock certain functionality: turn off Home, Volume, Off buttons, disable keyboard and touchscreen.

NB: To escape from Guided Access you should tap Home button three times and enter passcode that you have set up beforehand.

Other apps will be inaccessible while Guided Access is active.