https://www.gamespot.com/articles/how-to-download-fortnites-beta-on-android-update/1100-6461138/

Fortnite has launched on Android devices. The beta launched exclusively on Samsung devices last week, and now it's available on other Android platforms. However, you'll have to jump through a few hoops before you can jump from the battle bus. [Update: Epic has officially launched Fortnite for Android, doing away with the need for an invite to play it. We've got an updated guide on how to download Fortnite Android, but the important thing to keep in mind is that it's not on the Google Play Store. You'll instead download it from Epic's website, so just be sure you're on the real deal rather than an impostor site.

Epic is using a special Fortnite Installer on the company's website, so you're not going to find what you're looking for in the Google Play Store like other mobile games. Searching for "Fortnite" or "Fortnite Battle Royale" won't get you anywhere. What type of Android device you're using will determine where and how you install the game.