250 hours of rental services would have to be performed as a qualifier for the QBI safe harbor as it applies to rental properties. That means you along with your property managers would have to spend 250 hours of time attending to the management of your properties over the course of a year.
You may still be able to consider the rental business qualifying for QBI purposes even if it doesn't qualify under the safe harbor rules. This may be possible if you or the property manager devotes a significant amount of time managing the property and you have a profit motive as opposed to simply holding on to the property as an investment.