M.P.
I suggest that you don't want her to stay quiet at night because dreams are a way of processing our experiences and if dreams are the only way she can deal with kindergarten then she needs to dream and cry.
I suggest that she may be liking kindergarten and her friends because she is dreaming at night and dealing with things that way. I suggest that you could encourage her to talk about her feelings during the day so that she could process them before going to sleep and that might help.
I also suggest that she may need more emotional closeness to you and she gets this when you comfort her at night. I cried a lot at night when I was a child and looking back I'm aware that I needed my mother to hold and cuddle with me more. My mother was ill and wasn't very involved most of the time but she always comforted me when I was crying.
If you don't already, spend at least 30 minutes with her every evening. You can read together which often brings up subjects that a child wants to talk about. Go to the library and find children's books about things that seem related to what your daughter is dreaming. They don't have to be too closely related. There are lots of books about sharing which might be related. Most books will give you an opportunity to talk about life.
Let her know that you'll always take care of her. Give her lots of affection and opportunities to ask you questions and talk about experiences. Perhaps you can remember a time when you had dreams and/or felt sad and cried or wanted to cry. Tell her about when you were a kid her age. That often starts a good conversation.
She's crying because she needs to cry. Let her cry but find ways to spend close time with her during the day and she may not have the bad dreams at night.