This is endemic to many CERN projects, even things that are often open source are behind a login. Or - the source (or export of it from CERN's GitLab) will be available, but documentation is behind a login page.
Reminds me of Mozilla issues on GitHub and Bugzilla. You'll find important discussions that reference Google Docs documents with plans for architectural changes, roadmaps, or other details pertaining to the issue, but the documents are restricted to Mozilla employees.
This is especially frustrating if you want to learn more about the issue, or you'd like to contribute to the project.
