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
Millimetres, centimetres, who needs orders of magnitude? It’s great to hear this robot was able to pick up the 5km long piece of gravel the size of a small rodent