devtrackers.gg
This error typically means your phone thinks that Fortnite is still installed on your phone. You need to make sure the game and launcher are both uninstalled when you attempt to reinstall.
Make sure you check your phones storage and general applications to make sure that Fortnite is not on the device. Also uninstall the game first, then the launcher before attempting the reinstall. If you are having issues reinstalling please send me a direct message.