Getting unauthorized error while trying to access apis

I assume you got your URL from the example here: https://lithosphere.lithium.com/t5/Developer-Documentation/bd-p/dev-doc-portal?section=oauth2

it might be, that the /getAccessToken part of the redirect URL is just exemplary and therefore you'll get the error when calling your /authorize URL in the browser...what happens if you just redirect to your community home page and see if you get any URL params passed?