Count the items returned by a node

This workflow provides a simple approach to counting the items returned by a node. It uses a Set node with the Execute Once option: The expression uses $input.all() (documented here) to fetch all incoming items at once, and .length (documented for example here) to count them.

Help me set up the n8n workflow "Count the items returned by a node" (https://n8n.io/workflows/1913). It uses: Customer Datastore (n8n training). Import the template JSON into my n8n instance, list every credential I need to create, and walk me through testing it.