I have never used the guide but do know it works, I use CDs, many people experience difficulties making a bootable USB, then, the system has to support booting from the stick, have to read the thread again, do we know what make and model notebook you have, going to scroll up.
Check the instructions very carefully, I am thinking the instructions is assuning you have already made a bootable CD from the ISO you find in the compressed file.
Most people just use the ISO to make a bootablr CD with lot of goodies on it. The rest of the files are there to customize the content as in getting the latest definition updates for AVs and such as well as including any other program or files one might need then run the make ISO and burn an up-to-date boot CD, Let's concentrate on the ISO you find after you unzip what you downloaded and nothing else.
You most probably have to right click on that ISO and extract it to a folder (I use 7Zip and WinRAR, both give me option to right click a compressed file including ISOs then I select Extract to "****" 7Zip and WinRAR use the original file name where I put ****, You will have a sub-folder in the same folder as the original file.
Consider that folder the root of your CD as if you burnt the ISO on to a CD, I bet the person who wrote the guide is talking about that folder which will be identical to a burnt CD content.
Boy oh boy do I feel stupid and clumsy, got new set of ignition wires also got the distributor cap rotor and plugs, everything went smooth, almost, but me trying to clamp down the cap, put too much force on one of the hoses and broke it, daymn, these things happen right around the time they are closing, American tape "duct tape" to rescue till tomorrow phew ... be outside sweating some more