While Susie Glass is exercising, her ringing phone displays a call from 'The Duke' at 1736 (time); and later, when dressed, she answers a call from 'Unknown Caller' also at 1736.
Why, if Susie Glass is paranoid about being killed in her home by Collins, does she @24:52 go to answer the door, unarmed, to pick up a hamburger package? It doesn't make sense, seeing as, earlier, she was fearful enough to answer her door brandishing a pistol when The Duke / Eddie had made a surprise visit.
Lone women who are legally armed and do not expect visits after 5 p.m. would have their firearm in hand. Listening for the ring of the elevator carrying her order appeared to be her habit. Hopefully, she monitored the elevator and / or ground floor camera with her computer.