Save Auth0 token on web login to use for chrome extension

At the moment, we use Auth0 to log into our billing and customer management service. The issue is that we also are hoping to create a chrome extension to provide additional features, such as closing multiple related orders. What I am hoping to learn is how I can save some sort of token or cookie that is saved upon login that can then be reauthenticated via the javascript code when the extension is run. Ive tried following some other guides but since I am quite new to Auth0, im assuming im missing something here. Any suggestions or help is greatly appreciated.