Welcome to the bunnings Workshop community @Brodz19. It's fantastic to have you join us and many thanks for your questions.
The unit appears to be constructed of chipboard, but it is coated in laminate. You will be painting the laminate and will need to prep it as such. I would recommend using Zinsser 3.78L Extreme Adhesion Primer and then painting the colours in Dulux Aquanamel. The Aquanamel is a fairly strong paint and I don't believe it will need an additional coat to protect it.
I would think it is most likely best to paint the unit before assembling as it might be awkward afterwards.
You'll find the above method becomes fairly costly. As a cheaper alternative, you could scuff the laminate up with 80 grit sandpaper. You'll be wanting to remove all the sheen and smoothness from it. You can then spray paint it with White Knight Squirts 310g Spray Paint. A clear coat can then be put over the top to protect them.
Please let me know if you need further assistance or had questions.