I’ve not used the fedora installer, but from what I can tell you could try formatting sda6 with the filesystem you want and trying the installer again or maybe try clicking the + in the installer and see if it gives you the option to format sda6 and give it a mount point

Instructions for changing it here

https://wiki.archlinux.org/title/Firefox#XDG_Desktop_Portal_integration

Arch Linux is the same as the other day I think I will be in the office tomorrow so I can do it for you and you will be able to get it on the way to the office