一般フォーラム

tcolorboxで作ってみましたが, 以下のようにするのはいかがでしょうか。

\documentclass{jlreq}
\usepackage{tikz,tcolorbox}
\usetikzlibrary{calc}
\tcbuselibrary{xparse,hooks,skins,breakable}
\DeclareTColorBox{whitebox}{}{enhanced,colback=white,colframe=white}
\DeclareTColorBox{notebox}{o o o o}{enhanced,colback=white,colframe=white,sharp corners,breakable,height fill,top=4.2cm,bottom=2.3cm,
underlay={
\path[draw](frame.north west)--(frame.north east)--(frame.south east)--(frame.south west)--cycle;
\path[draw]([yshift=-1.5cm]frame.north west)--([yshift=-1.5cm]frame.north east);
\path[draw]([xshift=3.5cm]frame.north west)--++(0cm,-1.5cm);
\path[draw]([xshift=7cm]frame.north west)--++(0cm,-1.5cm);
\path[draw]([xshift=10.5cm]frame.north west)--++(0cm,-1.5cm);
\path[draw]([yshift=-3.5cm]frame.north west)--([yshift=-3.5cm]frame.north east);
\path[draw]([yshift=2cm]frame.south west)--([yshift=2cm]frame.south east);
\path[draw]([xshift=1.75cm,yshift=-3mm]frame.north west)node{\large Student};
\path[draw]([xshift=1.75cm,yshift=-7mm]frame.north west)node{\large Identification};
\path[draw]([xshift=1.75cm,yshift=-11mm]frame.north west)node{\large Number};
\path[draw]([xshift=8.75cm,yshift=-7.5mm]frame.north west)node{\large Name};
\path[draw]([xshift=1mm,yshift=-1.8cm]frame.north west)node[right]{\large Title};
\path[draw]([xshift=1mm,yshift=-3.8cm]frame.north west)node[right]{\large Abstract};
\path[draw]([xshift=1mm,yshift=1.7cm]frame.south west)node[right]{\large Keywords (5 words)};
\path[draw]([xshift=5.25cm,yshift=-7.5mm]frame.north west)node{\large #1};
\path[draw]($([xshift=10.5cm,yshift=-7.5mm]frame.north west)!0.5!([yshift=-7.5mm]frame.north east)$)node{#2};
\path[draw]($([yshift=-2.5cm]frame.north west)!0.5!([yshift=-2.5cm]frame.north east)$)node{#3};
\path[draw]($([yshift=1cm]frame.south west)!0.5!([yshift=1cm]frame.south east)$)node{#4};
}}
\begin{document}
\begin{center}
  \huge SUMMARY OF MASTER’S DISSERTATION
\end{center}
\begin{notebox}[1234][My Name][The Titile][Key Words]
  This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample. This is sample.
\end{notebox}
\end{document}

すでに解決されているようなので補足ですが、元の tblr 環境にオプション hspan = minimal を追加するだけで問題が解消します。

%!TeX = pdflatex
\documentclass{scrartcl}
\usepackage{tabularray}
\begin{document}

\begin{tblr}{
  hlines, vlines,
    colspec = {X[0.25,c,h] X[0.6,c,h]X[0.25,c,h] X[0.6,c,h] },
    cell{2-Z}{1} = {c=4}{},
    hline{3} = {0em},
    hline{5} = {0em},
    hline{7} = {0em},
    width = {\linewidth},
    hspan = minimal, % ⇐ これを追加するだけ
  }
  \SetRow{rowsep=5mm} Student ID & XXXX & Name & Tomy Otsuka \\
  \SetCell{l} Title & & & \\
  \SetRow{valign=t, halign=l}\SetCell{l} aaa & & & \\
  \SetCell{l} Abstract & & & \\
  \SetRow{valign=t, halign=l}{Abstract This paper compares a sample of 124 independent high technology entrepreneurs with 112 corporate entrepreneurs (intrapreneurs) involved in developing and introducing high-tech innovations across Canada. The study investigates the general management and technical problems faced by these entrepreneurs and contrasts their approach to such issues as market research, financing and production. The approaches used by the two groups in analyzing their markets and in planning and financing of innovations are compared and contrasted. In general, the independent entrepreneurs were technically trained, usually possessing engineering training but no general management training or experience, neither themselves nor members of their management team. Corporate entrepreneurs were as likely to come from management backgrounds as technical, or else supported their lack of general}
  &　& & \\
  \SetCell{l} Keyword & & & \\
  \SetRow{valign=t, halign=l} \SetCell{l} aaa & & & \\
\end{tblr}

\end{document}

加えて、添付ファイルでは \SetRow 等の表内のコマンドを使用しない方法を並記しています。