How to configure “On Element Click”

I followed your instruction mentioned here https://www.ads-software.com/support/topic/on-element-click-define-an-element-as-an-install-prompt-trigger/

but “On element click” not working for me. I choose On Element Click and mentioned “.install-app” in the element field. Copy-paste “<button class=”install-app”>Install now</button>” on WordPress page. When I click on the button nothing happens.