Download for Android
You get it directly from the Google play store or click on the below link. Just click on Install and wait for Downloading. You should have enough space on the device. The size of the app is 28MB. After Downloading you need permissions like for Camera and Mic. Your Android versions must be greater than 4.0.
For iOS and PC
This app is officially not available on the App store of apple. But can use it directly from the web browser. You can make shortcuts for quick access. This same logic applies to Desktops also.