To turn off ActiveX filtering in Internet Explorer, go to Tools 
In Skype for Business Web App, an ActiveX control—a small module that adds additional features to a web app or other program—is required for audio, video, and screen sharing.
Allow ActiveX controls to load and run
Depending on your organization, you may also need to change your Internet Explorer security options so that ActiveX controls work as expected:
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In Internet Explorer, go to Tools
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Scroll down to ActiveX controls and plugins, and select Enable under Run ActiveX controls and plugins and Script ActiveX controls marked safe for scripting.
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Select OK > OK, and close all Internet Explorer windows.
Important: If you made a change to the Script ActiveX controls marked safe for scripting setting, you must restart your computer for the change to take effect.
