In this guide, you will get to know how to “Unsupported OS”. You have to follow a few steps, and you can install Fortnite on your PC.
To download Fortnite on your PC, you must have the 64-bit version of Windows installed because you cannot download it on the 32-bit version of Windows.

Now you have to find out whether your PC has a 64-bit processor or not. To find out, go to the settings of your PC. You can also press the Windows key along Y to directly come to the settings. Now go to the System and move to the About option. Here you will be able to see the version of your OS.

If you already have a 64-bit processor and your OS is running on 32-bit, you only have to upgrade it. The upgrade will be free. You have to do a clean installation of your OS and reconfigure your applications to 64-bit processors. Your PC doesn’t keep up with 64-bit if you have an 86-based processor.
To upgrade to 64-bit, you must keep a backup on the external hard drive because the new installation will delete everything from the PC. It’s the only possible way to install the Fortnite game. For the proper working of the game, you must not have less than 4 GB of RAM.