What if an unemployed non custodial parent can only pay small fees every week instead of what they are asking?

My dad is unemployed but he still has to pay child support, which is understandable. But what if he can only pay maybe like $20 a week instead of what they're asking for? He doesn't receive unemployment or any of that, but we live with my aunts and they help us pay for what we need. How can we explain this to the child support system of New Jersey? They have sent us papers asking for an employer name but like i said before he is unemployed. Can someone help me out with this so i can explain to my dad?