drivers - During xmr-stak install (Monero Mining) I get CUDA TOOLKIT ERROR?

Here's the tutorial.

After

cd xmr-stak-cpu  

and

sudo cmake  

I get this error:

CUDA_TOOLKIT_ROOT_DIR not found or specified -- Could NOT find CUDA (missing: CUDA_TOOLKIT_ROOT_DIR CUDA_NVCC_EXECUTABLE CUDA_INCLUDE_DIRS CUDA_CUDART_LIBRARY) (Required is at least version "7.5") CMake Error at CMakeLists.txt:209 (message): CUDA NOT found: use -DCUDA_ENABLE=OFF to build without NVIDIA GPU support
-- Configuring incomplete, errors occurred!
See also "/usr/local/src/xmr-stak/CMakeFiles/CMakeOutput.log".`

I tried:

sudo cmake  

Once more, got a little different error:

-- Set miner currency to 'monero' and 'aeon'
CUDA_TOOLKIT_ROOT_DIR not found or specified
-- Could NOT find CUDA (missing:  CUDA_TOOLKIT_ROOT_DIR CUDA_NVCC_EXECUTABLE CUDA_INCLUDE_DIRS CUDA_CUDART_LIBRARY) (Required is at least version "7.5")
CMake Error at CMakeLists.txt:209 (message):
  CUDA NOT found: use -DCUDA_ENABLE=OFF to build without NVIDIA GPU support`
-- Configuring incomplete, errors occurred!

See also "/usr/local/src/xmr-stak/CMakeFiles/CMakeOutput.log".

---

I tried to install NVIDIA CUDA Toolkit from Nvidia website with the following errors:

-> runfile[local]

$ sudo sh cuda_9.1.85_387.26_linux.run

[sudo] password for username: 
sh: 0: Can't open cuda_9.1.85_387.26_linux.run

-> deb[local]

$ sudo dpkg -i cuda-repo-ubuntu1604-9-1-local_9.1.85-1_amd64.deb
dpkg: Error while processing the archive cuda-repo-ubuntu1604-9-1-local_9.1.85-1_amd64.deb (--install):    
The archive can not be accessed: file or directory not found    
Errors occurred while processing:    

cuda-repo-ubuntu1604-9-1-local_9.1.85-1_amd64.deb