I started the process on my own but found it very confusing as well. I would not get past the first step of the dataflowgroup process because, despite assurances to the contrary, it does not accept applications without a sponsor. My potential future employer asked me to drop it because they would take care of it themselves. They have so much more experience with the dataflowgroup thing than we do.
That's a complicated, longwinded, and specialist question. If you google HAAD license exam and nursing, there's actually a good bit online about it, particularly for nurses, including step-by-step guides for getting through the process. There's the occasional similar question on general forums like this, but it's a complex, frustratingly poorly described process and few answers can be found. I know. I'm going through it now for an allied health position and there's literally no help around. Unluckily for me, not much on Google either. Nurses have the best luck because so many of you have gone through it.
Best of luck!