I understand she did not “waltz into the other home” ...
Supposedly the doors open with a key or a code entry. She had reportedly tried thew key and it did not open the door. The man shot apparently heard someone at the door and opened it.
At some point after he opened the door, she shot him supposedly without entering the unit.
I was wondering previously how she reacted to the furniture not being hers. This would explain.
Correction: Tried the key.