That integration interface is very old - it likely isn't logging you in because at the time when it was created, I don't think the London data center existed.
Instead of using that integration there, I would recommend using DTM - place the embed code in the header and footer on your site, then use the DTM interface to establish rules and data elements to assign to Analytics variables. See this help page for more information: https://marketing.adobe.com/resources/help/en_US/dtm/deployment.html
Additionally, we will be running an Ask the Expert session on October 27th at 9AM MDT covering this exact topic. The session will be held at https://communities.adobeconnect.com/aemtech/.