ActiveX technology was developed by Microsoft in 1996 for sharing information and functionality among programs. ActiveX controls are browser plugins that provide additional functionality for Web browsers. Because of the security issues associated with ActiveX controls, they are not supported by default in most browsers including Mozilla Firefox. However, you can install them manually using an open source plugin for Firefox 39.
Download the ActiveX plugin from the host page. This is an open source plugin that provides ActiveX support for Firefox. Find the download link and download the plugin.
After the download is complete, close all open instances of Mozilla Firefox and run the setup, which installs the plugin on your computer.
When the installation is complete, open Mozilla Firefox and tap the Menu icon at the top-right corner to open the main menu. Then click the Add-ons icon to open up the Add-ons screen. On the Add-ons page, locate the Plugins tab and click on it.
On the plugins page, locate the ActiveX Hosting for Firefox plugin. You may need to scroll down the list to find it. Select an activation method from the drop down menu on the right side of the screen. This determines how the plugin is initialized. Once an option is selected, the plugin is ready for use. Restart Firefox to complete the installation.