As a first step, the user has to visit the OpenBeta testing page of BGMI on the Play Store.
After clicking on the link above, you will be taken to the Play Store page where it will ask for your consent to join the Early Access of Battleground Mobile India.
There you will see a page like the one given in the image below. Certain terms and conditions will be mentioned as well as a button to leave the program will be available.
In the second option a download link is given as shown in the image above. You can simply click on that link and you will be taken to play store page where Battleground Mobile India APK download button will be available.
Simply click on the Install button and your BGMI setup file will start downloading.