These numbers are what VMware validated doing intensive tests. Also there is one mistake on the number of concurrent workflows. It is 300 by default (and can be changed).

I know. I am checking why this number was used in this document and if this should be corrected or not. It may be a case of that it was not tested with a larger value even if default settings allows twice the number. I have done my own tests with throwing 600 workflows in parallel. 300 were running concurrently, the other ones queued. The test ran successfully. Now this does not make it the official numbers …

This is from the vCO 4.2 Admin guide:

"Modify the Number of Concurrent and Pending Workflows
By default, Orchestrator permits 300 workflows to run at the same time. When the Orchestrator server has to run more than 300 concurrent workflows, the pending workflow runs are queued. When an active workflow run completes, the next workflow in the queue starts to run. If the maximum number of queued workflows is reached, the next workflow runs fail until one of the pending workflows starts to run."