Help with terrified foster cat

Hello! I recently (1 Mon ago) started fostering a cat (~2 years old) for the first time ever. I’ve never had any pet so this has been a learning experience.

My lovely foster cat has had a tough time throughout her young life. Was a stray at the start, rescued and ended up being crated for ~18 mons, went to a foster home where other cats weren’t nice to her.

I’m working on socializing her and helping her gain confidence since she’s rarely ever interacted with humans who love her and expect nothing from her.

Since I’ve never had a cat, I’m not sure what to do with her to help her out. She spends the majority of the day in her crate, sometimes will come out to eat while I’m in the room but if I so much sneeze or move my hand, she runs and doesn’t come out again until I go to sleep.

I haven’t pet her once and she won’t even let me close enough to give her treats. She does growl when I come near her, only hisses if I catch her by surprise or get too close and even then, she is never physical. Doesn’t really move or act out physically.

She does explore and sometimes play when I go to sleep but I want her to start to feel comfortable to leave her crate in the day. It makes me really sad seeing her so stressed and scared all the time.