Single caption, double figure, figure notes, and left caption alignment

Question

I am using this template to write an article. I have the following to produce a side-by-side figure.

\documentclass[mnsc,nonblindrev]{informs3}
\begin{document}
\begin{figure}[ht]
\begin{minipage}{.49\textwidth}
    \FIGURE
    {\includegraphics*[width=1.08\textwidth,height=\textheight,keepaspectratio]{images/TCchangewithdifferentscenarios.png}}
    {Change in $\Bar{\sC}\left(k\right)$ given percentage improvement in $C^M_p$, $w_p$, $f$, and $\mu_p$ for $|\sP|=100$ and 100 replications.\label{fig:cost_change}}
    {}
\end{minipage}
\hfill%
\begin{minipage}{.49\textwidth}
  \FIGURE
    {\includegraphics*[width=1.08\textwidth,height=\textheight,keepaspectratio]{images/kchangewithdifferentscenarios.png}}
    {Change in $\Bar{k}$ given percentage improvement in $C^M_p$, $w_p$, $f$, and $\mu_p$ for $|\sP|=100$ and 100 replications.\label{fig:k_change}}
    {}
\end{minipage}
\end{figure}
\end{document}

This produces the below:

I have two objectives. First, I want to have a single caption for both of these figures and explanations below each as a) and b). Second, I want to left align all the Figure and Table captions in the manuscript.

I want to note that the template has its own rules for figure addition. Please refer to here (pages 7-8) for figure addition instructions to be able to follow why I use such a weird-looking method.

I checked here and some other posts and you may claim my post is duplicate. But, my question is indeed template specific. I want to achieve the desired results without causing any conflict (due to package additions) with the current template design. For example, when I use the example with subcaption, the template produces a warning which bothers me.