NSW Co-social case builder software not usable

At GovCampNSW I tried to use the GovCampNSW Co-social case builder to submit an idea. But this requires I register and that requires filling in a form in a pop-up web window. On my screen the fields to fill in are off the bottom of the screen and I can't scroll down. As a result of the flawed web design I can't submit an idea.

Some tests on the web page:

1. W3C Markup Validation Service: 56 Errors, 3 warnings
2. W3C mobileOK Checker: 42% critical 0, severe 3, medium 0, low 3
3. TAW Automated WCAG 2.0 Analysis level A: 4 Problems in 3 success criteria: Perceivable 2, Operable 0, Understandable 1, Robust 1