To be able to install EngageBox on an older Joomla version such as v3.3, v3.2 or even v2.5, you'll need to use an older release of EngageBox as well. The last compatible release is v2.2.1 (back then the extension's name was Responsive Scroll Triggered Box) and can be downloaded from the Releases Section where you can access any release. Notes: You will need an active subscription to be able to access any release. No support is provided for Joomla versions < 3.8.