https://www.mediawiki.org/wiki/Manual:Pywikibot/PAWS says running pwb.py at the PAWS command line "should confirm that you can log into https://test.wikipedia.org/ . It uses OAuth, so there is no need to enter a password."
Just now:
Sumanah@PAWS:~$ pwb.py login Password for user Sumanah on wikipedia:test (no characters will be shown): Logging in to wikipedia:test as Sumanah WARNING: API warning (login): Fetching a token via action=login is deprecated. Use action=query&meta=tokens&type=login instead. ERROR: Login failed (WrongPass). Password for user Sumanah on wikipedia:test (no characters will be shown):
Login depends on OAuth, but even though the user used OAuth to log into PAWS, the os.environ CLIENT_ID, CLIENT_SECRET, ACCESS_KEY, and ACCESS_SECRET aren't being set. So user-config.py can't find them, and the user cannot use Pywikibot to log into a Wikimedia wiki.