What do I need for a Red Claw Crab?

I want to get a Red Claw Crab. I have a 2 gallon tank. It came with a little filter made for tanks up to 3 gallons. Will I need the filter for the crab if he's the only thing living in there? Also, I have all kinds of fish food. I have like 3 kinds of flakes and some betta pellets. Will these be ok for the crab? I know they are scavengers so I have a feeling that he would be fine with any of these foods. I already have pebbles, plastic plants, and a way for him to get to the surface. I just want to know if he will need a filter and if those foods will be ok to feed him.