Practice using a screen reader and find your way around the page.
The challenges will not be read out using a screen reader by default as this website is only focussed on helping people unfamiliar with a screen reader to use one for testing.
Use your chosen screen reader either in 'blind mode' or in normal 'sighted mode' to see if you can complete all the challenges.
Blind mode will replace the visible area of the website with a VoiceOver help screen, meaning you can get help using VoiceOver whilst also obscuring the screen to stop you cheating!