Add-on you have already installed have a green corner banner with a checkmark. This opens a dialog showing Forms add-ons you can install from the Chrome Web Store.Click on the ' Load unpacked ' button, and locate the CRX file. Go to chrome://extensions/ and check the box for Developer mode in the top right. Download the CRX file to your computer for the Chrome extension you want to install.
So i donate whenever I can and encourage others to support vitaly in maintaining this perfectly formed plugin, that allows us to offer a preview of other websites on ours, without wrting anything more complex than the simplest - and excellently documented - shortcode.