You cannot start Animate (126.96.36.1999) on Windows 8.1
Install Animate Update 1 on Windows 8.1. It updates the Animate build to 188.8.131.528, which is supported and can be launched on Windows 8.1. For information about installing Animate Update 1 (13.0.1), see Download and install Creative Cloud apps. For information about the Windows 8.1 compatibility of other Creative Cloud applications, see Windows 8.1 compatibility FAQ.