Pattern for Parallel Sub-Workflow Execution Followed by Wait-For-All Loop

What this workflow does This (set of) workflow(s) shows how to start multiple sub-workflows, asynchronously, in parallel, and then wait for all of them to complete. Normally sub-workflows would need to be run synchronously, in series, or, if they are executed asynchronously (to run concurrently, in parallel), there is no easy way to merge/wait for an arbitrary number of them to complete. This is a "design pattern" template to show one approach for running multiple, data-driven instances of a sub-workflow "asynchronously," in parallel (instead of running them one at a time in series), but still prevent the later steps in the workflow from continuing until all of the sub-workflows have reporte

Help me set up the n8n workflow "Pattern for Parallel Sub-Workflow Execution Followed by Wait-For-All Loop" (https://n8n.io/workflows/2536). It uses: HTTP Request, Code. Import the template JSON into my n8n instance, list every credential I need to create, and walk me through testing it.