It can be downloaded from Chrome Store using the link: https://chrome.google.com/webstore/detail/subject7-smart-xpath/dfjdgoemofihnmfkoombfncangdehnla This link also includes couple of videos demonstrating the usage. You can set it up by following the article: https://subject7.zendesk.com/hc/en-us/articles/360008225273-Set-up-Gutenberg-Subject7-Smart-XPath-CSS-Generator-Engine-.