Setting table textwidth with \pgfplotstable

Question

I am trying to fit a table into textwidth using pgfplotstable. The code I found in this forum (here) somehow produces red lines and I do not know why this is the case.

This is how the results looks like. I do not understand what happens top/left. Also do you happen to know how to left-align the columns?

The biggest difference between my code and the code I found is that I am storing my data in a csv file. Any suggestions and solutions are highly appreciated. This is my code:

\usepackage{float}
\usepackage{pgfplotstable,tabularx,booktabs}
\pgfplotsset{compat=1.17}
\begin{document}
\begin{table}
\centering
\caption{\textbf{Caption} }
\label{caption}
\footnotesize

\pgfplotstabletypeset[
    column type=,
     begin table={\begin{tabularx}{\textwidth}{X c c c c}},
       end table={\end{tabularx}},
      multicolumn names, % allows to have multicolumn names
      col sep=comma, column type={l}, % the separator in the .csv file + column raggedleft
      display columns/0/.style={  column name=$ $, %first column because it is string type
        column type={l},string type}, 
      every head row/.style={
        before row= \toprule,% have a rule at top
        after row={
            \si{\ampere} & \si{\volt}\ % the units separated by &
            \midrule} % rule under units
            },
        every last row/.style={after row=\bottomrule}, % rule at bottom
    ]{Datafile.csv} % filename/path to file
\raggedright
\newline
\footnotesize{\textit{Sources}}
\end{table}
\end{document}