First of all it starts with an online application which is fairly straight forward from what i remember. once you've completed this you will either receive an email asking for you to register for a group interview or sorry you've not been successful, but they would like to keep your record on file, which they then mail every few month to see if your still interested. I applied in August 2017 finally got the group interview invite in January.
At the group interview you are shown a slideshow, a tour of the warehouse and shown what the process is. Then your asked to do 2 basic tests, one maths and one literacy. Very basic. Once you've passed that you will be invited to a one to one interview. If your successful at this stage you will be invited to a work trial which is between an hour and two hours, if you get this far you've pretty much got the job, just make sure your enthusiastic and ask questions. it does seem long winded but they pay well, so they will always have people wanting to work there.