I’d like to have the HTML5-output directly and automatically start. It is intended to be called from a webpage and if entered, it should not display the start-button (triangle) in the middle, it should start playing.
I guess you are running the output on macOS?
Unfortunately, iOS and recent versions of macOS don’t allow playing audio/video automatically inside a browser (even when controlling playback via script). The playback of media only happens if it is initiated by a viewer’s action. Since content created with ActivePresenter usually contains audio/video so clicking the Start button is required to display presentation properly.