Please install the appropriate browser extension. Note that the browser extension allows highlight in Confluence pages :

If you are looking for Enterprise Deployment of the extension, you can scale-up Smart Terms extension deployment in few steps :

When not using browser extensions, you can still use the Modal Highlighter and the Terms highlighter macro.

Please note that you can also disable the term's highlight through the browser extensions and hide the Missing live terms highlight? link through the Smart Terms configuration.