This is a general response to your question. For a more detailed answer, it depends on what scheduling software you are running on your HPC cluster, and if Parallel Server is installed on your cluster.
If MATLAB Parallel Server is installed on your cluster, you don't need to to anything to start up worker pools, the submission from the MATLAB client will do that for you. The way that you request specific resources is scheduler-dependent, but from within the cluster profile, you use the ResourceTemplate to select the resources you want -- which, dependent on how your scheduling software controls resources could be a queue, desired processor count, GPU, list of hostnames, etc.
When the job is submitted from the MATLAB client to the cluster, it passes the ResourceTemplate to the cluster and then the cluster assigns those resources to the job, runs the job, and passes the results back. All the scheduling, workers, etc are handled by the scheduler + install of Parallel Server on the cluster.
You might also find the batch command useful, as it will create a worker on the cluster on the job and then create the worker pool on the cluster, which then runs in the background and frees up your session.