Hi Nick! Cool article!

Coincidentally I'm the author of Dafiti's causal impact library :)

As it turns out I'm not quite sure what happened to the package but I'm afraid it's been deleted (I left the company a while ago and am trying to get in contact with colleges there to know what happened but so far the address returns 404).

As an alternative I'd like to suggest the newer package based on Tensorflow Probability:

https://github.com/WillianFuks/tfcausalimpact

It's the exact same thing but this time it follows a full bayesian description for the counter-factual and therefore results are equivalent to the original R package (I'm only maintaining this package as well).

Sorry for the inconvenience, unfortunately I have no control over dafiti's repos so as it seems that package won't be maintained there anymore =/.