DotNetBrowser doesn't support Google Chrome extensions. Google Chrome extensions integrate with Google Chrome app UI such as a toolbar, context menu, etc. So, it's expected that Chrome extension is running in Google Chrome.
DotNetBrowser doesn't integrate with Google Chrome app. It integrates only with web browser control that renders web content via Chromium engine. So, the library doesn't have Google Chrome UI required for extensions. This is why DotNetBrowser doesn't support extensions.