Background turned black instead of transparent while removing Greenscreen

I'm not proficient in any editing software, but I need to remove the green screen from over 200 video clips at once. Each clip is less than 5 seconds long, and I also need to export them individually with just one click. I searched for a solution on YouTube and decided to try Premiere Pro. I imported the clips separately and successfully removed the green screen. However, when I exported them separately using the "render and replace" option in single click, the background turned black instead of transparent. I want each clip to have a transparent background. Can someone help me find a solution, or suggest another software tool I could use?