Refugiums are relatively new to the hobby (to me anyway since I have been keeping fish since the 50's) No, they are not a requirement to have a successful tank. Yes, they help keep nitrates down-and used to be called
algae scrubbers and yes, you can grow copepods there, but you will have pods in your tank if you have enough good quality live rock and as the tank ages. YOu can also keep nitrates down through other methods, frquent, larger water changes, not overfeeding, making sure nothing dies and if it does get it out of the tank. Add some plants to the tank itself.
Do you have dragonets that live on pods? Most fish will eat a variety of fresh and frozen foods so it isnt necessary to proved additional pods.