I'm trying to export a video to have a transparency layer

I'm trying to export a video to have a transparency layer. These are the settings I have right now. Everytime I export it it keeps with a the black background which i want transparent. The one I did get correctly working only worked in an mpeg format. My client wanted it quicktime or something a bit smaller so that it would work with his obs display. He's trying to get it to run as a loop over a twitch stream.  Theres an animation over the T in the middle and everything thats is black in the picture is supposed to be transparent I'm not sure what I'm doing wrong.  Is there a driver I should have updated? Also it says quicktime is goin away soon so what should i do for that too>?