Victoria’s hydrogen buses will service routes across Footscray, Williamstown, Moonee Ponds and Sunshine in Melbourne’s west. The government said the trial, involving six operators, would provide information on how no-emission buses perform, including energy usage.
That’s your clue, there. Those areas all belong to Transit Systems: https://www.transitsystems.com.au/hydrogen-bus-new
You can try calling or emailing them, but you’ll probably have better luck going to Footscray station and asking the staff there. They’ll know the bus numbers and when they’re next due to arrive.