I'm experiencing the same issues. I found I could eventually (hours of troubleshooting) get past the first page and if I select a basic install (no Web). If I go back and edit the deployment, it goes back to the same thing.
I've been working with FileMaker Support for months trying to troubleshoot why the Admin Console is so slow and they insist that it is a 3rd Party application like McAfee. They won't offer any help and they insist that NASA has it installed and it works (sorry the FM rep I spoke to was sarcastic and not very helpful).
Try turning off any anti-virus, restart the FileMaker process, and try the deployment assistant again.