That error ("is not supported for account") means your Databricks account hasn't been enrolled in the private preview for NCC private endpoints. The feature is currently in private preview, so even if you follow the documentation steps correctly, the API will reject the endpoint creation until Databricks enables access for your account on the backend.

The fix is to reach out to your Databricks account team or open a support case and ask them to enable the private connectivity / NCC private endpoints private preview for your account. Once they flip that switch, you should be able to continue from step 2.2 without any changes to your configuration.

You can also check whether your AWS region is among the ones currently enrolled in the preview when you make that request, since regional availability can vary during preview phases.