MVVM closing dialog form from ViewModel

Question

I want to show a window to create an object based on a form my users fill.

What I do now is from my main view model, I instanciate my form window, set its datacontext to a new instance of the corresponding viewmodel class and get ShowDialog()

        var addLicWnd = new AddLicenseWindow();
        if (addLicWnd.ShowDialog() ?? false)
        {
            var x = ((AddLicenseWindowViewModel)addLicWnd.DataContext).dialogResult;
            //dialogResult is a property I set in my VM to get the data back when the form closes
        }

This ViewModel exposes a dialogResult property to get the data back from the form to my main ViewModel where I will then add it in DB etc ...

My problem here is I cannot close the form within it from a button press for example.

What I found is an answer from a similar question ( https://stackoverflow.com/a/3329467/9734355 ) But the only way I found to use it is to call this SetDialogResult method which takes the window as a parameter. Which means I need to have a reference to my View inside my ViewModel, hence breaking MVVM (or did I miss something?)

So it would look like

Main ViewModel

        var addLicWnd = new AddLicenseWindow();
        addLicWnd.Datacontext = new AddLicenseWindowViewModel(addLicWnd);
        if (addLicWnd.ShowDialog() ?? false)
        {
            var x = ((AddLicenseWindowViewModel)addLicWnd.DataContext).dialogResult;
        }

Form ViewModel

    public Window window;
    public event PropertyChangedEventHandler PropertyChanged;
    public LicenseRecordModel dialogResult;

    //Commands and OnPropertyChanged...

    public AddLicenseWindowViewModel(Window w)
    {
        window = w;
    }

    private void ButtonClick(){    
        dialogResult = new LicenseRecordModel("b", "b", "b", "b", "b");
        //...
        DialogCloser.SetDialogResult(wnd, true);
    }

This works but does not look MVVM compliant to me, what should I do? Did I misunderstand the answer?