To access Dubbing Studio, you first need to create a Dubbing Studio project.
To do this, create a new Dubbing project, making sure to select the 'Create a Dubbing Studio' option.
It's not possible to convert an existing automatic dub to a Dubbing Studio project.
The Dubbing Studio project will appear at the top of your list of dubbing projects, and will go through various stages while generating.
Once it has completed processing, and the Status is 'dubbed', you can click 'Edit' to enter Dubbing Studio.
For more information about Dubbing Studio, please see our overview.