First, I am sorry you have to experience this. Blending families can be difficult. My step-mother would definitely say the same.
Firstly, your husband DID NOT have your back when he moved her in without you having any choice, the fact that he is trying now is good, but he could have avoided a lot of misery at least letting you acclimate first. Now I am on your side about having structure and rules, etc. There should be clear expectations on things like dating, chores, etc. Those should be discussed and then told to her by her father, who should also have his share of implementing them (which means you will need to do some of that, but with specific set-up discipline). This is his child, and if he expects to have another he should be primarily responsible for this one. You are a part of his team, so instead of fighting discuss strategy, but ultimately this is his.
That being said, this is hard on her too. She has a dad who threw her at you, he is gone all of the time, and her life may have been VERY different from what it is now. Kids are never good with change, and if her mother isn't involved (since she isn't mentioned and she is living with you mostly full time I will say that is safe to assume) she needs guidance.
You can't ignore that she is there because your husband chose to make that your problem. Ignoring her for 4 years isn't going to help either of you. It only makes a kid bitter and resentful and a step-mother who is turned rotten and has to put of the dreams she has for a family.
The nice thing is that you can sit her down and hash out what you are willing to do for her, see what she wants out of you, and make adjustments. Find out what attention she does need, and give it to her if you can or at least find someone who will. You aren't her mother, sounds like she doesn't want you to be, but that can be a good thing. It's common ground at the very least.
Her dad 100% HAS to front-run rules, he can stand up to his family all he likes, but his daughter is the one it will make all the difference with. You don't have to be her friend, but as a housemate and the daughter of your husband she deserves your cordiality and kindness. You need to determine what that means, and how much responsibility for her you want to take on. Make that clear to your husband, and follow through with your step-daughter.
If something isn't working, try something different, and keep trying different things until you get it. Then later if it stops working, try something else entirely.
Things won't be perfect, but hopefully they will get better. Whether you try anything, best of luck to all three of you.