Problem: When I start AP I get this error message: Failed to initialize multimedia library. Audio/video will not function properly.
ActivePresenter version: ActivePresenter Free Edition
Version 8.4.0 - 64-bit build. (Released: 2021.04.29)
OS: Windows 10
Did you try following the steps in this thread to see if it helps?
Also, kindly note that if your computer has any virtual audio device, please try disabling it too since ActivePresenter doesn’t work well with some devices of this type.