A newbie can not use CUDA by follow official DOC!

The driver is installed (I mean linux recognize it, so I am assuming it is fine). I followed this post CuArray can't find libcuda - #7 by cuchxq
to make the library discoverable, but it still fails.

When I write

using Libdl
Libdl.dlopen("/usr/local/cuda-10.2/targets/x86_64-linux/lib/stubs/libcuda.so")

it outputs:

Ptr{Nothing} @0x0000000002b63b40