Google requires that you login with a Google account before you can install any Chrome extensions.
The following is how to install an extension without logging in (under Windows. The same should work under Linux and Mac):
- Find the ID for the extension. When you browse the extension in the store you will see a URL similar to the following: https://chrome.google.com/webstore/detail/cookies/iphcomljdfghbkdcfndaijbokpgddeno?hl=en. The hash string after the ‘cookies’ string (the name of the extension) up to the ? is the id.
- Download the .crx extension file. Use the following URL and replace the <ID> string with the ID for your extension: https://clients2.google.com/service/update2/crx?response=redirect&x=id%3D<ID>%26uc. Chrome will complain that the extension cannot be added from this site. Just ignore/OK it and you will be able to download it.
- Download and install (if you don’t already have it) 7zip.
- Create a directory and move the .crx file into it. Go into that dir, rename the .crx file to .zip and use 7zip to extract the file.
- Then back in chrome enter the following URL: chrome://extensions/
- Towards the top-right of the page, check the “Developer Mode” checkbox.
- Then click on the “Load unpacked extension…” button and navigate to the directory that contains the unpacked .crx file and select it and it should install the extension for you.