To add closed captions to your video:
Click Generate on your video.
Use the toggle to include closed captions.
Select the blue Generate button.
Caption will be included.
To exclude them, toggle the caption option off.
To learn how to edit your captions, see: How do I edit closed captions on my video?
Notes:
If you choose to either include or exclude captions your video, your viewers won't be able to turn them on or off.
Use the video 3-dot menu to download your video subtitles/captions once the video is generated.