I should have mentioned that I can access the release repository which is selected from the downloads page. The information on the certificate page says:
This is your certificate to authenticate your client to pkg.oracle.com. It is valid for every repository hosted on pkg.oracle.com. However, to download packages from a certain repository you will have to request access first. You can do that on the Repositories page.
But it does not give access to the support repository. And I can't see any link to request access to it.
I had to get software support access.