Making orthogonal arrows in Forest

Question

This appears as a basic question but I guess its important for those beginning to learn forest using the working example in this question (which typically looks like the Figure 2 here). I would like the first arrows of the parent look as shown in Figure 1. I have been trying this for a while and haven't figured it out. I also think it would also be beneficial to others if I ask here. I have used the code in the link provided as a benchmark.

Edit: I edited the first MWE and modified the one in the linked question for clarity. The problem is that following the style in Figure 2, when the children "Straighten the Arrows" in this diagram increases to say ten columns. The arrow from the parent begins to cross some of them.

\documentclass{article}
\usepackage{forest}
\usetikzlibrary{shadows,arrows.meta}

\tikzset{parent/.style={align=center,text width=2cm,fill=green!20,rounded corners=2pt},
child/.style={align=center,text width=2.8cm,fill=green!50,rounded corners=6pt},
grandchild/.style={fill=pink!50,text width=2.3cm}
}
\begin{document}
\begin{forest}
for tree={%
thick,
drop shadow,
l sep=0.6cm,
s sep=0.8cm,
node options={draw,font=\sffamily},
edge={semithick,-Latex},
where level=0{parent}{},
where level=1{
    minimum height=1cm,
    child,
    parent anchor=south west,
    tier=p,
    l sep=0.25cm,
    for descendants={%
        grandchild,
        minimum height=0.6cm,
        anchor=150,
        edge path={
            \noexpand\path[\forestoption{edge}]
            (!to tier=p.parent anchor) |-(.child anchor)\forestoption{edge label};
        },
    }
}{},
}
[Forest
[Straighten
    [ 
        [ 
            [ ]
        ]
    ]
]
[The
    [
        [
            [
                [ ]
            ]
        ]
    ]
]
[Arrows
    [
        [
            [
                [
                    []
                ]
            ]
        ]
    ]
]
]
\end{forest}
\end{document}

Answer 1

There are quite a lot of examples of this structure already. The following is adapted from https://tex.stackexchange.com/a/299500/, where explanatory notes can be found.

\documentclass[border=10pt]{standalone}
\usepackage[edges]{forest}
\usepackage[T1]{fontenc}
\tikzset{%
  parent/.style={align=center,text width=3cm,rounded corners=3pt},
  child/.style={align=center,text width=3cm,rounded corners=3pt}
}
\begin{document}
\begin{forest}
  for tree={
    % edge+={->},% uncomment for arrows
    draw,
    rounded corners,
    node options={align=center,},
    text width=2.7cm,
  },
  where level=0{%
    parent anchor=children,
  }{%
    folder,
    grow'=0,
    if level=1{% this changes the edges from level 0 to nodes at level 1
      before typesetting nodes={child anchor=north},
      edge path'={(!u.parent anchor) -- ++(0,-5pt) -| (.child anchor)},
    }{},
  }
  [LMS, fill=gray!25, parent
  [Funktionale \\Anforderungen, for tree={fill=brown!25, child}
  [Lerninhalte organisieren]
  [Lerninhalte erstellen]
  [Lerninhalte abfragen]
  [Kommunikation]
  [Benutzerkonten\-führung]
  [Steuerungs\-funktionen]
  ]
  [Nicht-Funktionale Anforderungen, for tree={fill=red!25,child}, calign with current edge
  [Zuverl{\"a}ssig\-keit]
  [Skalierbar\-keit und Effizienz]
  [Benutzer\-freundlich\-keit]
  [Portierbarkeit]
  [Datenschutz / Informationssicherheit]
  [Erweiterbar\-keit]
  [Anpassbarkeit]
  ]
  [Technische Rahmen\-bedinungen, for tree={fill=blue!25, child}
  [System\-architektur]
  [Software\-kriterien]
  [Schnittstellen]
  [Wartung und Support
  [Support\-leistungen]
  [Software-Pflege]
  ]
  ]
  ]
  ]
\end{forest}
\end{document}

EDIT

To address the edited question, one way to get the desired effect is to set parent anchor=center for the root node and make the parts of the edges which overwrite the node invisible. You could put them on a background layer using the background library. Or you could just use `blend mode=lighten. For example,

\documentclass[border=10pt]{standalone}
\usepackage[edges]{forest}
\usepackage[T1]{fontenc}
\tikzset{%
  parent/.style={align=center,text width=3cm,rounded corners=3pt},
  child/.style={align=center,text width=3cm,rounded corners=3pt}
}
\begin{document}
\begin{forest}
  for tree={
    % forked edges,
    draw,
    rounded corners,
    node options={align=center,},
    text width=2.7cm,
  },
  where level=0{%
    parent anchor=center,
  }{%
    folder,
    grow'=0,
    if level=1{%
      before typesetting nodes={child anchor=north},
      edge path'={(!u.parent anchor) -| (.child anchor)},
      edge+={blend mode=lighten},
    }{},
  }
  [LMS, fill=gray!25, parent
  [Funktionale \\Anforderungen, for tree={fill=brown!25, child}
  [Lerninhalte organisieren]
  [Lerninhalte erstellen]
  [Lerninhalte abfragen]
  [Kommunikation]
  [Benutzerkonten\-führung]
  [Steuerungs\-funktionen]
  ]
  [Nicht-Funktionale Anforderungen, for tree={fill=red!25,child}, calign with current edge
  [Zuverl{\"a}ssig\-keit]
  [Skalierbar\-keit und Effizienz]
  [Benutzer\-freundlich\-keit]
  [Portierbarkeit]
  [Datenschutz / Informationssicherheit]
  [Erweiterbar\-keit]
  [Anpassbarkeit]
  ]
  [Technische Rahmen\-bedinungen, for tree={fill=blue!25, child}
  [System\-architektur]
  [Software\-kriterien]
  [Schnittstellen]
  [Wartung und Support
  [Support\-leistungen]
  [Software-Pflege]
  ]
  ]
  ]
  ]
\end{forest}
\end{document}

If your edges are lighter than the node, rather than darker, use blend mode=darken instead.