I see where I went wrong with my tutorial, I did not say that fluxbb must be downloaded and installed.
this is why there is confusion. I have updated the tutorial
FluxBB must be installed, you can download it from (We developed this with version 1.4.8)
It is best to install it in the root of your website under a directory for example fluxbb
functions.php file found at : <directory where fluxbb is installed>/include/functions.php
I hope this make more sense ? If not please let me know.