The Onboarding Test test confirms that your device is compatible and will allow you to familiarise yourself with the platform before the assessment. You should complete this at least once before each assessment.
If you're sitting the final assessment remotely, you should also complete the Proctored Onboarding Test. This will confirm that your device is compatible with the online invigilation software and show you how to set up on the day.
For more information, please review the Assessments Fundamental.