If you aren't familiar with the extension, it can be summarized as a:
Tool for security analysts, malware hunters, and incident responders that allows the use the of right-click menu in Chrome to conduct single or group searches for selected text such as file hash, IP address, or domain. The extension reduces time analysts spend visiting the same websites repeatedly to gather information about IP addresses, websites, file hashes, and domains.
The SA web GUI is shown below. The extension will automatically configure if you copy and paste the base investigation URL as shown below. For a manual configuration you will need the fully qualified domain name (IP address), HTTP or HTTPS, and device ID.
Paste the URL in the text box shown below highlighted in yellow.
You can create your own pivots (queries) or just use the defaults Critical Start supplied.
An example of the extension in action can be seen in the screen shot below showing FireEye integration with Security Analytics. The Critical Start integration with FireEye and Security Analytics gives more options that what FireEye provides.