Cubico example notebook data download fails

[jordanperr]

While running the example notebook 02b_plant_aep_analysis_cubico.ipynb i ran into the following issues:

1. SSL error downloading data when on VPN.
2. Even when off VPN, downloading is slow and the progress isn't clearly reported.
3. The download eventually fails with Missing/incomplete configuration file: /home/vscode/.cdsapirc

[RHammond2]

Would adding an important alert at the top of the cell indicating that a registration is required for both the CDS and MERRA2 data be helpful? This would essentially restate the content of "Step 1", but higher up and be much harder to miss.

[jordanperr]

Adding a warning box might be a good idea. But as this is expected behavior I will close the issue.