The security warnings are only about the CADviewer I see so far. That part of the site, i.e. when clicking on some of the drawings opened a browser plugin on the old website which doesn't any more since many years. Don't try to install that old plugin, it would not work anyway in any of the current browsers.

Some time ago I tries to open the drawings with an alternative tool, but failed. I'll try again soon and will update here in case it works.