Xiaomi, after Mi Note Pro, gives them with the boot-loader locked and with the original chinese/english rom which doesn’t have inside Gapps (Google Apps). Xiaomi Redmi 3S and Redmi 3S Prime are the latest mid-range devices. In that case you will have to install Gapps (which includes Google Play Store) manually.
So let us see how we can manage it in just 3 step:
Step 1: You will have to download to your device this file – Google Installer. Inside the zip file you will find 3 apk files. You must find the Google Installer 2.0.apk. You can also download the file to your pc, unzip it and copy it to a folder at the memory of your mobile.
Step 2: Press on the file to install it and follow the onscreen instruction to complete the whole process. It will take 5-10 minutes, depending the mobile and your internet connection. At the end you will see a “Ok” button, click on it. Do not click on the “Launch” button during installation.
Step 3: Accept all terms and condition. Log in to your account to complete the installation. Check before if you have problems with the internet connection and don’t interrupt the procedure, as you will have to do it all over again from the beginning.