It happened because Chrome blocks autoplay for non-muted content and creates a media engagement index (MEI) for every website based on user engagement. Chrome will allow videos to autoplay when the MEI score for a website is above a certain value. More information about Google Chome autoplay rules you can find on the link.
In LMS365 Mobile App, by default, we use WebView with emulation Google Chrome browser. That emulator uses the same auto-play policy as the Chrome Desktop version. To resolve this case, change the Default Browser on your mobile device to Firefox, for example.