Your child wants to feel safe. She feels safest when she is in close proximity to you. Because familiarity breeds comfort – that’s how her brain is wired.
When she was a baby, her cries signaled you to pick her up and give her the safety and touch she was craving. Your child is desperate for her own felt sense of safety now too, just as she was when she was that little baby.
Give her structure and boundaries that are clear. Let her know when you will leave, how long you will be away for and when you will be back. Tell her once, and help her find familiarity in the routine of what happens when you aren’t home. And stick to that routine each time.