I get an ignoring play button in the start of all my projects when publishing them.
How do I get rid of that?
You can't due to changes that browsers are making regarding things that are set to auto-play. Browsers are beginning to not allow audio and video from automatically playing in a page if the user hasn't interacted with the page yet. This is why the play button now appears when you publish files from Captivate 2019 as it requires that you interact with the page by pressing the play button thus your video and audio will play along with the slide.
Have a look at:
AutoPlay preventing existed since quite a while for mobile devices, but Chrome now also does it for desktop browsers. No way to escape, better learn to live with it.