Usepackage Forest - Wie kann ich nodes in den Rechtecken erzeugen?

\documentclass[11pt,a4paper,titlepage,bibliography=totoc,numbers=noenddot,abstract=on,multi,dvipsnames,svgnames,x11names]{scrreprt} 
\usepackage{forest}

\definecolor{folderbg}{RGB}{124,166,198}
\definecolor{folderborder}{RGB}{110,144,169}

\def\Size{5pt}
\tikzset{
  folder/.pic={
    \filldraw[draw=folderborder,top color=folderbg!0,bottom color=white]
      (-3*\Size,-\Size) rectangle (3*\Size,\Size);
      \coordinate (X) at (0,0);
  }
}
\forestset{fmark/.style={label={[at={(X)},anchor=center,font=\sffamily]left:#1}}}

\begin{document}

\begin{forest}
  for tree={
    font=\ttfamily,
    grow'=0,
    child anchor=west,
    parent anchor=south,
    anchor=west,
    calign=first,
    inner xsep=20pt,
    edge path={
      \noexpand\path [draw, \forestoption{edge}]
      (!u.south west) +(4pt,0) |- (.child anchor) pic {folder} \forestoption{edge label};
    },
    before typesetting nodes={
      if n=1
        {insert before={[,phantom]}}
        {}
    },
    fit=band,
    before computing xy={l=60pt},
  }  
[system
  [config,fmark=A
  ]
  [lib,fmark=C
    [Access,fmark=1
    ]
    [Plugin,fmark=3
    ]
  ]
  [templates,fmark=F
  ]
  [tests
  ]
[tests
]
[tests
]
[tests
]
[tests
]
[tests
]
]
\end{forest}
\end{document}