We are aware of an issue where some players are unable to log into Fortnite on Android devices and it's being investigated.
In the meantime, you can try some basic troubleshooting steps: How do I troubleshoot crashes, errors, and performance issues in Fortnite on Mobile?
If that doesn't help, you can try installing a different Internet browser on your phone and launching Fortnite there:
- Uninstall Fortnite
- Install a new browser on your phone
- Reinstall Fortnite and launch the game
Note: The app will prompt you to choose between the browsers installed on your device to proceed with the log in. - Select the newly installed browser
- Log in to your Epic Games account.