(It also works if your desktop is connected via Ethernet.) Make sure your desktop and phone are connected to the same Wi-Fi network. Open the app on your Android phone and give it permission to access your camera and microphone. You should see the DroidCamApp icon on your desktop.Follow the setup wizard's installation instructions.
iPhones need to be on iOS 9 or later, and you can check by going to Settings > General > About > Software Version. To check, go to Settings > About Phone > Android version. (Your Android phone needs to be running Android 5.0 or higher.