Spent the better half of a day tapping and clicking around the internet. Save yourself the headache.. check out https://www.win-acme.com/

It’s a command prompt based LetsEncrypt installer that’s MAGIC.

Remember to have incoming ports 80 and 441 open or it will fail.  Apart from that the instructions are self explanatory.

I’ve attached a screenshot of the interface (well.. a screenshot of their screenshot.. inception)

Pro Tip: Remember to open command prompt as Administrator (right click command prompt) or it may not work.  I tried to take a screenshot but ..  Mac + remote deskotop = no bueno