LaTeX Error: File `kbordermatrix.sty' not found

Question

I have the code for a transition matrix that compiles fine with a desktop editor like TeXstudio, however fails to compile in cloud-based LaTeX editors like ShareLaTeX or Overleaf:

\documentclass{article}
\usepackage[utf8]{inputenc}
\title{test}
\author{me}
\date{June 2015}
\usepackage{kbordermatrix}

\begin{document}

\begin{equation}
\kbordermatrix{
    & S_1 & S_2    & S_3    & S_4 \\
S_1 & a_{11} & a_{12} & a_{13} & a_{14} \\
S_2 & a_{21} & a_{22} & a_{23} & a_{24} \\
S_3 & a_{31} & a_{32} & a_{33} & a_{34} \\
S_4 & a_{41} & a_{42} & a_{43} & a_{44} \\
}
\end{equation}

\end{document}

ShareLaTeX fails to compile this document and reports the error LaTeX Error: File 'kbordermatrix.sty' not found. Click here to see for yourself:

https://www.sharelatex.com/project/55777d19fb8b79874d8f1694

Why does TeXstudio have no problem compiling this code, while Overleaf & ShareLaTeX fail to compile the very same code?

The strange thing is, I get this error even though I have loaded the kbordermatrix package with the command \usepackage{kbordermatrix}. What can I add to my code to make this compile? (Preferably, since this is cloud-based, I would rather simply add some code to my document instead of uploading a file.)

Thank you for your help!

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Edit: For reference, here are some other tex.SE answers regarding kbordermatrix:

Array with labeling columns

Labeling the columns of matrices

Matrix with rows and columns labeled

Where is the \matrix command?