iPhone asks to allow a VPN configuration

The first time you connect, iOS asks to add a VPN configuration and may ask for your passcode or Face ID. This is a standard iOS prompt and the app cannot connect until you allow it. If you declined it earlier, go to Settings, then General, then VPN & Device Management, remove any old configuration for this app, and connect again to get a fresh prompt. If another VPN app is installed, make sure it is disconnected — only one VPN can be active at a time.