Hi @arup.sarkar,
Thank you for your response.
Based on the URL you shared, you redirected to http://localhost:3000 successfully. The code and state parameters are expected as part of the response. You can see an example of it here.
Note that if the redirect_uri in your request does not match one of the Allowed Callback URLs on your application settings, you will get an error.
With that said, the http://localhost:3000/?code=abcd&state=1234abc response URL is correct and to be expected.
The next step is to request the tokens using the code you obtained.
Hoped this helps!
Thanks.