If you are an Android user, download PUBG Mobile from the Play Store. If you are an apple user then download it from the App Store.
Click the install button and the download will begin. But remember that the game is 1.5 GB larger, I would advise you to use WiFi. If you want to use mobile data at night, so that you use your remaining data Sometimes even after completing the download it shows an error and is not installed so keep this in mind. If you can not find PUBG in your Play Store, it means that your phone is not supported for this game.