First BRRRR looking for the right contractor and bid

[Alexis A Peinado]

I have been interviewing and showing contractors around my first BRRRR project. It's a duplex and of course needing some work but also I'm looking to convert a 2 car garage into a 3rd unit on the property. So far all the contractors are taking a long time to come back with numbers but in addition they just seem to just give a lump sum of what it will cost. They don't seem provide an itemized list, one even asked what I would like to see on the list. Am I missing something on my end? Do I need to provide a breakdown of what I want done and they just plug in numbers next to each item? And as far as I noticed they are all licensed and bonded and one has even taken me to one of his work sites. Maybe it's a thing in this certain area?