Since it looks like you have an internet connection issue (or connection to the GitHub server at least), not having an issue with the actual HollaEx Kit installation part, it is technically irrelevant to HollaEx Kit.
If you are still having the issue, you should contact your internet service provider or review your computer’s settings to ensure nothing is blocking the connection to GitHub.
You’re right, I tried a different connection and it immediately worked.
I tried a few times with my previous connection and it kept throwing that same error. I can see it was ostensibly a curl error, but thought it might have been something else because I hadn’t had any problems with GitHub up until then. Bizarre, but not particularly surprising, I guess.