I have installed python 2.7.3 on a Windows 8, 64 bit machine, sublime text and nltk 3.0.1 with the following steps:
Install Setuptools: http://pypi.python.o
This work for me on macOS 10.15
Search for 'Install Certificates.command' in finder and open it.
Now,
import nltk nltk.download()
It will open the NLTK downloader then you can select and download the required package.