You do not need to submit an application form as StepUp eligible students are automatically assessed by TISC. The TISC system will automatically step your ATAR up to 70 if you have met the eligibility criteria and have also met one of the 'eligibility measures'.
They will add in the Bonus Points if you have already achieved 70 or above and have attended a StepUp eligible School.
This information will show on your University Admissions Advice Letter (UAAL) that you receive when you have completed the WACE exams.
The only category that is not automatically assessed by TISC is for Financial Hardship; if you are applying based on Financial Hardship you will need to complete the StepUp Application Form.