I've just altered Step 2.5 by adding, "If you have a UEFI computer you must choose the option in the menu to boot the USB as UEFI not legacy because Step 11 depends on it. If you have an old Bios [non-UEFI] computer then you do not have this complication, just select the USB and Step 11 will work anyway.".

I found this out a few minutes ago by doing it wrong.

All the best,
Denis