Extremely Aggressive Cat

I am currently doing drop ins on a very aggressive cat. I did a meet and greet the day before I started and kitty was so affectionate toward me with mom around. The next day I had one drop in. Complete 180. Hissing, swatting, chasing me, yowling, stalking me, lunging, attacking my legs, etc. Even if I completely ignore her she still comes after me and is almost always growling. It’s hard to even feed her and clean her litter boxes. Today during my morning drop in, she trapped me in the closet with the litter box while I was cleaning it and attacked me. (The room is a closet with a small door at the bottom for the cat to get through). I used a trash can to block her but she keeps getting my feet and it hurts. I try to stay away from her but she continues to seek me out even though the apartment is quite large. Do you guys have any advice? I have to do 2 drop ins a day for the next 4 days so any thoughts are welcome. Thank you in advance :)