I have tried multiple times with multiple browsers but still could not start creation of a test DB.
My CDS is still connected and the admin panel shows me "Upgrade jetzt ausführen" (probably "Start the upgrade" in the english localization). When I click this link, I land on the upgrade page explaining the steps with the "Testdatenbank erstellen" - Button (probably "Create Test DB" in english localization). However, this button as well as the currency and language fields is not clickable.
I searched the forum and did not find anybody with the same problem - starting even before step 1.
Do you solve your issue?
And could you please reference this
Hope this could be helpful.