Open Google Chrome and enter "chrome://extensions/" into address bar ("More Tools | Extensions" from menu) to open the extension page, find the switch "Developer mode" in the upper right corner and turn it on.
Click "Load unpacked" button and browse to the unzipped folder.
By doing this, you can experience the new version in advance or install the plugin in cases where you cannot access the Google Chrome Web Store.
However, please note that versions installed in this way won't receive automatic updates and won't share data with versions downloaded from the Chrome Web Store.
Make sure you have only one Unisat Wallet plugin installed in the same browser to avoid conflicts.