To use the Dolby provided temporary storage is a two step process.
You start by declaring a dlb:// url that you can reference in any other Media API calls. The response will provide a url where you can put your media. This allows you to use the dlb:// url as a short-cut for a temporary storage location.
You'll be returned a pre-signed url you can use to PUT and upload your media file. The temporary storage should allow you to read and write to the dlb:// locations for a period of at least 24 hours before it is removed.