I JUST NEED THE APP FOR MY CELLPHOND
It’s probably not possible in any sort of elegant way. Phone screens are small and applications hard to hook into. There could be like a pop-over that simultaneously streams the subtitles on top of your app but with such a small screen that’d be really cumbersome.
It’s highly unlikely that there will ever be a mobile app. It would need to bypass the Netflix app and would probably get a cease and desist letter very soon. If you need to use LLN with a mobile device your best bet is probably to get a Windows tablet.