Must the owner's representative be the owner in the property management regulations?

Not necessarily. If the owner can't be present in person because of going abroad, traveling and other reasons, he can only entrust others to represent the rights and obligations of the owner, but in general, he needs a power of attorney from the owner. Because property rights determine the right to operate, if it is not owned by the owner, it cannot fulfill its rights and obligations, but if it is entrusted, it is legally possible.