Questions first, sis, so I can give you answers that can be specific to your needs.
#1. Are you based abroad?
#2. Are you planning to lease out your unit on a short, or long-term, basis?
#3. Do you have any trusted family members/ friends to help you with monitoring your unit?
#4. What are you willing to pay your property manager?
#5. What exactly do you expect your property manager to do?
Phexchanger is correct, sometimes the developer can assume the role of unit manager. This is provided that your unit is enrolled in their leasing program, and of course, they will take a percentage of your monthly rentals.
Pros: You don't need to find tenants
you don't need to take care of tenants' complaints, etc.
Depending on the agreement with your developer's leasing arm/department, they will be the ones to take care of housekeeping, upkeep, maintenance, repairs (to a certain point), etc. etc.
Cons: If there are so many units in a building, usually potential clients will go find a broker who handles properties in said bldg. Why? Mas madaling tumawad.

If developer's leasing arm handles so many units, and they don't get plenty of inquiries, there's a possibility na mababakante unit mo ng matagal. Unlike brokers/ agents who ACTIVELY promote their inventory, leasing arm, bihira.
You are locked in with the leasing arm for X period of time. Exclusive listing nila unit mo. If you don't like the way they manage your unit, sorry, wait til your contract runs out, or pay the opt out fee.
Hope I helped somehow.
