Evaluation setup using "I have an account and want to generate a key" fails

After downloading and installing Confluence 5.8.2, and choosing the evaluation setup, and choosing no plugin bundles to evaluate, I get to the /setup/evallicense.action.

If I choose the middle "I have an account and want to generate a key" option, and provide a correct Atlassian ID username and password, after a few seconds I get the error:
"An unknown error occurred, please contact support"