How to Install Google Play Store On MIUI 8
1) First, download the Latest Google Installer apk from here and save it on your device.
2) Now enable the Unknown Sources. To enable Unknown Sources, go to phone settings –> Additional Setting and enable the Unknown Sources.
3) Now open the file manager and browse for Google_Installer.apk file.
4) Now to install the Google Installer on your phone just click on apk and run the file.
5) Open the Google Installer app after the installation complete.
6) Now click on the blue button. This will install all the play services on your device.
7) Done! This will Install Google Play Store and Play Services On MIUI 8.
Reboot your device after installing Google Play services.So this is the complete guide of how to manually Install Google Play Store On MIUI 8 devices. If you have any doubts comment below.