Fortnite

Epic states the iPod touch 6th generation is not supported, which matches the error shown above.

The following is a screen capture of the App Store page for Fortnite, with the iPod touch 6th generation unsupported info highlighted:

While you could certainly confirm the official answer directly with Epic Support, the error message and the App Store page both indicate iPod touch 6th generation is not supported by Fortnite.

I strongly have to agree with everyone else who responded to you.

Fortnite IS NOT compatible with the 6th generation iPod Touch.

It is made very simple and clear in your screenshot!

Like MrHoffman, my reading of the message is that Fortnite is not supported on the 6th generation iPod.

Re-read what it says;

Fortnite does not support: and then it lists the versions of iOS it does not support. That list includes iPod Touch 6th gen.

It says it’s not supported, so the minimum specs must be above what the 6th gen runs.