ConnectionError in graphLoader()

I downloaded ML workbench to local pc through command ‘git clone’.
And I am trying to run hgat_node_classification.ipynb file.
Until Visualizing Schema & Counting Vertex/Edge, It works well. But it makes an error when i try to run graphLoader() Function.

Someone who knows what to do in this case?

Version. Tigergraph 3.7.0 Enterprise Free Edition

Have you activate ML workbench on your database?

No I didn’t.
Do I have to do the following process with the enterprise-free-edition also?

You can download the developer version here, or you need to request an access key for the enterprise version. The easiest way, however, would be provision a TigerGraph Cloud instance with the ML Workbench starter kit