Unable to authenticate google api - google-contacts-api

Question

I have followed everything on this website here. I have also downloaded the .json file with my client ID and client secret and put it in the same folder as my python file. When I run my code, I am able to login, but after I continue to let my google app access my google account, it crashes. I am not receiving any access tokens at all either. Does anyone know why this is happening?
This is the quickstart.py file
from __future__ import print_function
import datetime
import os.path
from googleapiclient.discovery import build
from google_auth_oauthlib.flow import InstalledAppFlow
from google.auth.transport.requests import Request
from google.oauth2.credentials import Credentials
# If modifying these scopes, delete the file token.json.
SCOPES = ['https://www.googleapis.com/auth/calendar']
def main():
"""Shows basic usage of the Google Calendar API.
Prints the start and name of the next 10 events on the user's calendar.
"""
creds = None
# The file token.json stores the user's access and refresh tokens, and is
# created automatically when the authorization flow completes for the first
# time.
if os.path.exists('token.json'):
creds = Credentials.from_authorized_user_file('token.json', SCOPES)
# If there are no (valid) credentials available, let the user log in.
if not creds or not creds.valid:
if creds and creds.expired and creds.refresh_token:
creds.refresh(Request())
else:
flow = InstalledAppFlow.from_client_secrets_file(
'credentials.json', SCOPES)
creds = flow.run_local_server(port=8080)
# Save the credentials for the next run
with open('token.json', 'w') as token:
token.write(creds.to_json())
service = build('calendar', 'v3', credentials=creds)
# Call the Calendar API
now = datetime.datetime.utcnow().isoformat() + 'Z' # 'Z' indicates UTC time
print('Getting the upcoming 10 events')
events_result = service.events().list(calendarId='primary', timeMin=now,
maxResults=10, singleEvents=True,
orderBy='startTime').execute()
events = events_result.get('items', [])
if not events:
print('No upcoming events found.')
for event in events:
start = event['start'].get('dateTime', event['start'].get('date'))
print(start, event['summary'])
if __name__ == '__main__':
main()

Answer 1

I was used google contacts API to export contacts with nodeJS. I made documentation also where you may find out how you generate access tokens.
How does it work?
The first time you run the sample, it will prompt you to authorize access:
I assume that you got that step and accept/allow button. Now you are so close to generating the access token.
Now,
Copy the code you're given, paste it into the command-line prompt, and press Enter. After this, The file token.json stores the user's access and refresh tokens, and is created automatically when the authorization flow completes for the first time.
For further details see this, maybe it will help you.
google-contacts-api