OP your poor dd this must be a horrendous situation for her. It sounds as though she is blocking you out and very unhappy and angry and scared. It is likely she does not understand your explanations about hurting others, because she feels so disconnected herself, she has no way of making connections. In reality she has no control over her situation, she has no way of rationalising her behaviour or making connections with consequences. It sounds as though she isn't good at explaining how she feels or thinks and it might be that it has been so long like this, all her thoughts and feeling are now jumbled up and confused - and she is still very young, at 7 - and so she doesn't actually know how she thinks and feels much of the time. And so she is stressed, anxious and panicking and in fight/flight mode, and then when you are angry or disappointed or withdraw it makes her panic more and more and it becomes even more unmanagable.
And it then seems to you that she has no emotions.
What you could do is sit down with her and say you are sorry that things are so hard, and that you are going to do your best to make things better, and that you will sort this out, she doesn't have to worry. You will of course have the same day to day struggles with routine and talking to her about doing what she is told and about her behaviour and social skills but if you make sure you set aside time to just be with her, talking and giving her positive attention, whatever else has happened in the day, this will really help.
In that time, if you start to talk to her as much as possible she will very slowly start to have a vocabulary to explain her thoughts and feelings, and for her to understand her own thoughts and feelings. Maybe have small expectations at first, but try to help her know and understand and verbalise her thoughts and feelings slowly over time, and the relationship will start to build. Make it all about her at this time, not you. Maybe start with "do you like blue or red?" "what is your favourite tree?" just to give her practice at thinking about what she thinks and talking about it. Try to help her talk about her own struggles for example at school and think up strategies to help her. Show her empathy so that she is learning from your modeling. Do kind thngs for other people with her, so that she learns how but also how good it feels to be kind to others. And from you, when you are kind to her, so she learns how good it feels when someone is kind to you.
She will then slowly start to trust you, and in those early days you will see glimpses of that, and of the sort of connection you could have.
All this hard work work has to come from you, I am afraid - she does not have the maturity or the skills to slowly build the relationship with you. External people cannot do this for you. She needs help to slowly get to know herself and for her to start building on firm foundations which will enable her to fulfil potential and build relationships with school friends and so on into the future.
There is a website about parenting which gives information about child development, what to expect when etc, which is important baseline information for adopted children. It is also good in relation to parenting, building connections with your dc, building relationships with your dc, self care.
If on the other hand she really does not show any emotion ever - no screaming or losing her temper, etc - then she would need specialist help, but I have assumed that isn't the case, that it is more that she doesn't show empathy.
I am an adult adoptee, and parent, not an adopter by the way.