@monkia, Thank you, I appreciate your feedback!

Thank you for your feedback and advises.
The problem is that I cannot change the project or the supervisor, I can only leave my position. There are two calls per year when applications are received and each position is open for a specific project. So the only option is to change the institution and probably the country.
I wonder if I would dare to risk with another PhD position after this experience, although I feel like PhD is something well suited for me.

Hey all,

Recently I've started a PhD in an institute where I did my master's thesis. At the time when I was submitting my application, there were no any positions suitable for me in the same group where I worked, so I applied for a PhD topic in another group at the same institute. The project was kind of on a similar track to what I was doing for my master's. Group leaders of my previous group where happy with my work and I got a good recommendation and it was fairly easy to get the position.
Although I liked the project description and the idea, it was quite vague, without details. Even during the interview I didn't get much more information as the project was just about to begin, and even group leaders were not hundred percent sure in which direction to go. I decided to take a risk and accept the position, mostly because the institute has excellent labs, I liked the atmosphere, the city and the country, the position is fully funded etc.
Three months after the beginning, I feel like it was a bad decision. First of all, I don't like my role in the whole project, I am not even sure that it is suitable for a PhD. I am 100% dependent on another group and the work they are expected to deliver, whereas the work that I am supposed to do (at least in the first year of my PhD, but probably more) is not something new or innovative, and basically is worthless without the work of the other group. In this situation I feel like am not fully under control of my PhD, if they fail, I fail too.
There are other things that are bothering me like the fact that most of the people from the group are working on something quite different and I don't feel like I have a good support and somebody I can ask specific questions. Also, after three months I still don't have materials I need to work with, and they haven't been ordered yet so it will take another few months before I can start working.
Has anybody been in a similar situation? Any advice would be appreciated. Should I stay and give it a chance, or leave?