If you see a Log in required message during MCP authorization, your browser is not currently signed in to Kolleno. The authorization step happens in your browser, so it needs an active Kolleno session.
Click Open Kolleno on the page (or open Kolleno in the same browser) and sign in. Then return to the authorization page and click I'm logged in — continue. This fixes the problem in most cases.
If it still fails, check that your browser isn't blocking third-party cookies (common on Safari and some privacy-focused browsers), that you're not in a private/incognito window, and that you signed in with the correct Kolleno account. If the issue persists, contact support.