So the drainage tray goes under the cage. This way when you mist the water does not flood your floor. You can either modify the tray with a hole and pvc piping to drain into a bucket or use a wet vacuum to pull the water out.
The bundle comes with two wedges for a misting system. I recommend the Mistking misting system. It comes with one nozzle and you would just buy a plastic tote or bucket with lid for the water reservoir it pumps from. You can buy this on Josh's frogs
https://www.joshsfrogs.com/mistking-starter-misting-system-version-4-free-shipping.html
Use the code reptiliangarden15 when you buy from joshs frogs and you will save 15% on your order.