<ol>

  <li><a href="ReactDevTools.zip">download extension</a></li>

  <li>Double-click to extract</li>

  <li>Navigate to <code>edge://extensions/</code></li>

  <li>Enable "Developer mode"</li>

  <li>Click "LOAD UNPACKED"</li>

  <li>Select extracted extension folder (<code>ReactDevTools</code>)</li>

</ol>