The External Spoofing Engine is a separate process that is managed by Kameleo. External browsers (such as your mobile device's browser) can connect to it as an HTTP proxy.
Once the profile is started the connection info is printed by Kameleo. For your Android device, you can simply use the QR code to connect. When you want to connect your Opera, you need to connect manually.
This uses the same spoofing mechanism as our built-in browsers, but as you connect with your own browser there can be little glitches with your browser fingerprint when you are using it. So basically, we recommend you to use our built-in browsers.