Filing permit for adding the fence in front of building

Hi
We are a 4 story small condominium in Brooklyn. We plan to add fence in front of building and are told permit is required, because we are not the 1 or 2 family home. I’ve inquired with some of fence companies, but they don’t file permit and don’t know how to do it. Do we have any resource about service that we can hire to file permit and know the rule of DOB?