Loans to buy, not build, future new construction

Hey Everyone I’m looking at a four unit that has yet to be built. It’s zoned with septic, but the structures haven’t been started. I wouldn’t be building it myself, but rather locking in an offer with a preapproval and down payment, then closing later when everything is complete. My portfolio lender initially said no, as I think he misunderstood that I’d need a construction loan. When I explained the facts, he said he wasn’t sure and would look into it. So my question is, can buying to be built construction work the same as real property if it’s really just a preapproval up front (with contingencies would be fine), then a much longer waiting period to close? In the end, the real property would exist be the time bank funds would need to change hands. Thank you!