Thanks so much for your reply _az. Much appreciated!
Yes, the OS on my laptop is Windows10. To replicate the same environment to which I am deploying in prod, I need Ubuntu Linux, so using Vagrant+VirtualBox with a Linux “box” (OS). On that Linux box, Docker is installed and bringing up NGINX/Certbot/Pebble as Docker containers. But yes, the very underlying OS (on my laptop) is Windows, and correct, it’s a dev environment that will be deployed to Linux, so can’t run Certbot natively on Windows. 
Is there a reason why colons need to be used in the folder name on Linux? Is it possible for Certbot to avoid using colon “:” in folder names, regardless of OS?
In lieu of that, is there another possible workaround? Maybe pass a flag like "–use-safe-folder-names"or something like that to the “certbot” command, or set an ENV?
Thanks again so much for your insight and help to try to resolve this. 