ELITE licenses only. If this is disabled, it's because you have a Pro license (Upgrade)
When you prepare a Video or Audio for streaming (see Streaming vs. Progressive Downloads), S3MediaVault submits a job to AWS MediaConvert to create the streaming files (aka, split up the mp4/mp3 file into smaller, encrypted chunks of data).
This page lists all of the streaming jobs in your AWS account.
If the status of a streaming job says "Complete", that's when the streaming video shortcode will start working correctly on your pages.
If there are no jobs listed here, or if a job shows an error, then your shortcode will not work. In that case, please make sure the credentials entered in the S3MediaVault Settings page are correct and prepare the Video/Audio for streaming again.
If that still doesn't help, please open a support ticket.