Python sdk error DropboxAuth2Flow

Okay, so I tried importing all the modules required to run this script as below and there are no errors.

from dropbox import DropboxOAuth2Flow, oauth
import http_status
from flask import flash

APP_KEY = 'mykey'
APP_SECRET = 'mysecretkey'

def get_dropbox_auth_flow(web_app_session):
    redirect_uri = "https://my-web-server.org/dropbox-auth-finish"
    return DropboxOAuth2Flow(
        APP_KEY, APP_SECRET, redirect_uri, web_app_session,
        "dropbox-auth-csrf-token")

# URL handler for /dropbox-auth-start
def dropbox_auth_start(web_app_session, request):
    authorize_url = get_dropbox_auth_flow(web_app_session).start()
    redirect_to(authorize_url)

# URL handler for /dropbox-auth-finish
def dropbox_auth_finish(web_app_session, request):
    try:
        oauth_result = \
            get_dropbox_auth_flow(web_app_session).finish(
                request.query_params)
    except oauth.BadRequestException as e:
        http_status(400)
    except oauth.BadStateException as e:
        # Start the auth flow again.
        redirect_to("/dropbox-auth-start")
    except oauth.CsrfException as e:
        http_status(403)
    except oauth.NotApprovedException as e:
        flash('Not approved?  Why not?')
        return redirect_to("/home")
    except oauth.ProviderException as e:
        logger.log("Auth error: %s" % (e,))
        http_status(403)

But it doesn't seem to open up the browser for authentication from the user. Am I missing something?

It looks like you're referring to the example code in the DropboxOAuth2Flow documentation. That example code isn't a complete sample, so it won't work on its own. For instance, it doesn't include definitions for `redirect_to` or `http_status`. It's just meant as an outline of how you would implement this in a web app using a web framework.

First, to clarify, are you building a web app using a web framework? You don't need to use Flask in particular, but the expectation for that sample is that you would be using some framework that provides the functionality for `redirect_to` or `http_status` (or that you would build your own). In that case, the line `redirect_to(authorize_url)` would send the user to the Dropbox OAuth app authorization page.

You said that you're "trying to build a simple python script that will let user authenticate using browser", so it sounds like you may not be building a web app, but rather a local app. In that case, you would still need to have the use the browser to have the user authorize the app, but you're not in a context where you can just redirect them there. In that case, DropboxOAuth2FlowNoRedirect may make more sense for your use case. There's a small sample in the documentation for that too that may be helpful.