dot net core authorization example

Hello, I am trying to build a blazor app to be able to sync my lists on a click.

I followed the steps from the API Docs on - "OAuth2 Authorization Code Flow" but I realized the popup to sign in to Constant Contact is not showing up.

I used the httpclient to make a call to 

https://authz.constantcontact.com/oauth2/default/v1/authorize?

 and added the following parameters ofcourse:

client_id={your_client_id}&redirect_uri=https%3A%2F%2Flocalhost%3A8888&response_type=code&scope=contact_data%20campaign_data%20offline_access&state=235o250eddsdff

I get a 200 and when I read my httpresponse as string I do see the login html page from constant contact but I dont see a popup?

Is there a dot net 6 example app that anyone can refer me to?

Thanks in advance!