Why doesn't WordPress video play also without autoplay?

From the official Apple WebKit documentation (iOS):

Starting in iOS 10, WebKit relaxes its inline and autoplay policies to make these presentations possible, but still keeps in mind sites’ bandwidth and users’ batteries.

By default, WebKit will have the following policies:

• video elements will be allowed to autoplay without a user gesture if their source media contains no audio tracks.
• video muted elements will also be allowed to autoplay without a user gesture. If a element gains an audio track or becomes un-muted without a user gesture, playback will pause.

https://webkit.org/blog/6784/new-video-policies-for-ios/

As for Mobile Chrome (Android):

Muted autoplay for video is supported by Chrome for Android as of version 53. Playback will start automatically for a video element once it comes into view if both autoplay and muted are set, and playback of muted videos can be initiated progamatically with play(). Previously, playback on mobile had to be initiated by a user gesture, regardless of the muted state.

https://developers.google.com/web/updates/2016/07/autoplay

Example:

 <video id="myVideo"muted defaultMuted autoplay playsinline controls>     <source src="myVideo.mp4" type="video/mp4"> </video>

Your video preview shows the video file is not working. You should see a thumbnail of the video file such as this:

I'm not sure why, but it could be that the file on the server was moved/renamed/deleted since you added the video to this page. One explanation it is working on Edge but not mobile is perhaps the image was cached previously on the Edge browser.

If you remove the image and try to re-add it through Elementor, can you reproduce the problem?

Another idea is you may have a slightly corrupted video file. Try editing it in any video-editing program (several free online ones) and see if exported file works in your page.