Ubuntu 16.04: fresh installation of CUDA-8.0 (Debian) only contains one folder called 'extras'. Where are the other folders?

I am new to Ubuntu and CUDA. I have been trying to install CUDA-8.0 on my Ubuntu system. Once I have downloaded the Debian version of the file from https://developer.nvidia.com/cuda-downloads

(cuda-repo-ubuntu1604-8-0-local-ga2_8.0.61-1_amd64.deb) I follow the instructions as suggested. However, when I go to /usr/local/cuda-8.0 there is only one ‘extras’ folder. I have tried the installation several times and this continues to happen.

I looked at this

https://devtalk.nvidia.com/default/topic/1007838/only-extras-file-exists-in-usr-local-cuda-8-0/

but it isn’t relevant to my problem. I am using Ubuntu 16.04 (I should add, that I am using a GUI on my machine, and the company that supplied the machine has told me that I need the Debian version - I have tried the runfile but I get an X-driver error).