Authorisation Code method redirect issue

I’m hoping someone can help with a stumbling block I’m facing with our auth flow. I’m trying to use the Authorisation Code method outlined in the api docs (https://developers.taboola.com/backstage-api/reference#authorization-code) as follows:

This flow is similar to Implicit Grant (above), but involves an additional step:

User clicks on Connect within your App.
Your App redirects the user to a Taboola login page:
[authentication_domain]/authentication/oauth/authorize/?client_id=[client_id]&redirect_uri=[redirect-uri]&response_type=code
Note: set authentication_domain = 'https://authentication.taboola.com’

I’ve built the Taboola login url as outlined above using our client id and desired redirect however when I test the URL and subsequent login process there is no redirect back to our app, instead the user is taken to this page within Taboola that asks whether I want to go to backstage or newsroom, both of which keep the user in Taboola.

Anyone know why I can’t redirect back out to our app to complete the authors flow?