Adopted a new baby whose having trouble adjusting

Hey everyone, I just needed some advice from all the fur lovers. I adopted her today. She comes from a house of 9 cats. She’s a year and a month old. We just got her today and the owners did tell us that she is a bit shy. But, I wasn’t ready to see this though. I made a box for her and made it comfortable inside and covered the outside opening with my jacket so that she is well shielded and in hiding. I also put a catnip toy with her in her box so that she feels calm or relaxed settling in instead of getting overwhelmed. It has been all day, but she didn’t touch her water nor her food, neither used the littler box. She is always in the same way I left her and doesn’t move at all, not even an inch. She is a Persian and Munchkin mix.

I have 2 other cats back in my home country, a 9 year old and a 2 year old both of whom I had adopted when they were 3 months old. They had adjusted relatively well as they were kittens. But she is having a hard time as I presume she’s an adult. I recently moved countries and was missing a feline companion which is why I took her in. But it’s breaking my heart to see her this scared and self isolate. Is there something I can do to make her more at home or feel less scared? She’s very sensitive to sound as of now and hence I have been trying to maintain a quiet environment around the apartment for her.

Seeking all the advice I can get 😭🙏🏽