I guess that at least the admin user record is missing, if not the whole ISPConfig database. Do you have a phpMyAdmin where you can check that?
Also, it is a pain to go through the install so many times. Can you save it at anypoint to start over? Just not having to type the cert stuff would be helpful.
No, you have to run the whole installation again. Delete the directories /home/admispconfig
before and also the ISPConfig database if there is one...