Installing the sgtk module manualy

Hello,

I followed all documentation from Initialization and startup — tk-core v0.20.19 documentation
and I can’t use pip install for sgtk
I download it manually and add python folder to PYTHONPATH, but when I try to import
from sgtk.platform.qt import QtCore, QtGui get error ImportError: cannot import name ‘QtCore’ from ‘tank.platform.qt’
I can do that in python console of Shotgun Desktop itself but not locally on my Computer.

Best Regards,
Danijel