LaTeX Beamer -- How to create numbered table captions without the table environment

I'm trying to create a numbered table caption in beamer without using the table environment. The reason for not using the table environment stems from the possibility of horizontal aligning my tables.

I'm using a command "\myCaptionGrey" to create a table caption, but I don't understand how I can add a numbering.

Here's my MWE: (Side note: For my needs I like to use the NiceTabular environment)

\documentclass[aspectratio=169,xcolor=table,12pt]{beamer}
% compile in pdfLaTeX

\usepackage{caption}
\usepackage{booktabs}
\usepackage{nicematrix}
    \NiceMatrixOptions{cell-space-limits = 2pt}

\definecolor{tableYellowHeaderBg}{RGB}{250,191,18}
\definecolor{tableYellowCellBg}{RGB}{255,242,204}
\definecolor{tableYellowLines}{RGB}{250,191,18}
\definecolor{tableYellowCellFg}{RGB}{127,127,127}

% table caption
\newcommand{\myCaptionGrey}[2]{%
  {%
    \usebeamercolor[fg]{tableGreyCellFg}%
    \usebeamerfont*{caption name}%
    #1%
    \usebeamertemplate{caption label separator}%
  }%
  \usebeamerfont*{caption name}
  #2\par
}

\newcommand{\myCaptionYellow}[2]{%
  {%
    \usebeamercolor[fg]{UnthaTableYellowCellFg}%
    \usebeamerfont*{caption name}%
    #1%
    \usebeamertemplate{caption label separator}%
  }%
  \usebeamerfont*{caption name}
  #2\par
}

\begin{document}

    \begin{frame}[t]{Tables}

        \raggedleft
        \myCaptionYellow{Table}{This is a table caption.}
        
        \begin{NiceTabular}[c]{wc{1.0cm}wc{1.0cm}wc{1.0cm}wc{1.0cm}}[rules/color=tableYellowLines]
        \CodeBefore
            \rowcolor{tableYellowHeaderBg}{1}
            \rowcolors{2}{}{tableYellowCellBg}
        \Body
            \toprule[1.5pt]
            \RowStyle{\color{white}}H1 & H2 & H3 & H4  \\
            \arrayrulecolor{white}\toprule[1.5pt]
            \RowStyle[nb-rows=*]{\color{tableYellowCellFg}}Cell 1 & Cell 2 & Cell 3 & Cell 5 \\
            \midrule
            Cell 5 & Cell 6 & Cell 7 & Cell 8 \\
            \midrule
            Cell 9 & Cell 10 & Cell 11 & Cell 12 \\
            \bottomrule
        \end{NiceTabular}
        
    \end{frame}

\end{document}

Solution

Here a variation which includes the figure/table number (please note that the syntax is now slightly different, the first argument should be table or figure in lowercase).

I would also suggest to not repeat the same definition for multiple different colours. Instead you could change the caption name beamer colour.

\documentclass[aspectratio=169,xcolor=table,12pt]{beamer}
% compile in pdfLaTeX

\usepackage{caption}
\usepackage{booktabs}
\usepackage{nicematrix}
   \NiceMatrixOptions{cell-space-limits = 2pt}

\definecolor{tableYellowHeaderBg}{RGB}{250,191,18}
\definecolor{tableYellowCellBg}{RGB}{255,242,204}
\definecolor{tableYellowLines}{RGB}{250,191,18}
\definecolor{tableYellowCellFg}{RGB}{127,127,127}

% table caption

\newcommand{\myCaption}[2]{%
 {%
   \refstepcounter{#1}%
   \usebeamercolor[fg]{caption name}%
   \usebeamerfont*{caption name}%
   \csname#1name\endcsname~\csname the#1\endcsname
   \usebeamertemplate{caption label separator}%
 }%
 \usebeamerfont*{caption name}
 #2\par
}


\begin{document}

   \begin{frame}[t]{Tables}

       \raggedleft
       \setbeamercolor{caption name}{fg=tableYellowCellFg}
       \myCaption{table}{This is a table caption.}
       
       \begin{NiceTabular}[c]{wc{1.0cm}wc{1.0cm}wc{1.0cm}wc{1.0cm}}[rules/color=tableYellowLines]
       \CodeBefore
           \rowcolor{tableYellowHeaderBg}{1}
           \rowcolors{2}{}{tableYellowCellBg}
       \Body
           \toprule[1.5pt]
           \RowStyle{\color{white}}H1 & H2 & H3 & H4  \\
           \arrayrulecolor{white}\toprule[1.5pt]
           \RowStyle[nb-rows=*]{\color{tableYellowCellFg}}Cell 1 & Cell 2 & Cell 3 & Cell 5 \\
           \midrule
           Cell 5 & Cell 6 & Cell 7 & Cell 8 \\
           \midrule
           Cell 9 & Cell 10 & Cell 11 & Cell 12 \\
           \bottomrule
       \end{NiceTabular}
       
       \raggedright
       \myCaption{table}{This is a table caption.}
       
       \begin{NiceTabular}[c]{wc{1.0cm}wc{1.0cm}wc{1.0cm}wc{1.0cm}}[rules/color=tableYellowLines]
       \CodeBefore
           \rowcolor{tableYellowHeaderBg}{1}
           \rowcolors{2}{}{tableYellowCellBg}
       \Body
           \toprule[1.5pt]
           \RowStyle{\color{white}}H1 & H2 & H3 & H4  \\
           \arrayrulecolor{white}\toprule[1.5pt]
           \RowStyle[nb-rows=*]{\color{tableYellowCellFg}}Cell 1 & Cell 2 & Cell 3 & Cell 5 \\
           \midrule
           Cell 5 & Cell 6 & Cell 7 & Cell 8 \\
           \midrule
           Cell 9 & Cell 10 & Cell 11 & Cell 12 \\
           \bottomrule
       \end{NiceTabular}
       
   \end{frame}

\end{document}