Windows Arrayfire C library loading error even after using ctypes to help debug

It seems there is a missing DLL problem that prevents Arrayfire from running on a new installed Windows machine.
The Python (3.7.1) is installed through Anaconda, and the Arrayfire binary installation file and Visual C++ Runtime 2015 are also installed. All in x64 version (so not exactly the same as #166).
However, when importing in Python by `import arrayfire`, I still get the following error
```
RuntimeError: Could not load any ArrayFire libraries.
Please look at https://github.com/arrayfire/arrayfire-python/wiki for more information.
```
To distill the cause of the error, I use ctypes to import the arrayfire DLL to see if it is successful, only to find that the DLL file cannot be loaded either
```
In [2]: import ctypes
In [3]: import os
In [4]: dll_path = r'C:\Program Files\ArrayFire\v3\lib\afcpu.dll'
In [5]: os.path.exists(dll_path)
Out[5]: True
In [6]: ctypes.cdll.LoadLibrary(dll_path)
---------------------------------------------------------------------------
OSError Traceback (most recent call last)
in
----> 1 ctypes.cdll.LoadLibrary(dll_path)
C:\ProgramData\Anaconda3\lib\ctypes\__init__.py in LoadLibrary(self, name)
432
433 def LoadLibrary(self, name):
--> 434 return self._dlltype(name)
435
436 cdll = LibraryLoader(CDLL)
C:\ProgramData\Anaconda3\lib\ctypes\__init__.py in __init__(self, name, mode, handle, use_errno, use_last_error)
354
355 if handle is None:
--> 356 self._handle = _dlopen(self._name, mode)
357 else:
358 self._handle = handle
OSError: [WinError 126] The specified module could not be found
```
It seems that a dependent DLL is missing but the error message is not very helpful....