Installation failing - tensorflow 1.10.0 not found

I replaced python 3.7 with 3.6. Now I am getting another:

Command “python setup.py egg_info” failed with error code 1

I followed a solution I found online and upgraded set-up tools

pip install --upgrade setuptools

And now I am getting YET another error:

Could not install packages due to an EnvironmentError:

/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/_markerlib/markers.pyc’

And why is it referring to version 2.7 above?