The Lone-Coder/letsencrypt-win-simple v1.9.1 is stable and we’ve tested it successfully on Server 2016, 2012R2, and 2008R2. The Let’s Encrypt certificates are requested, installed and renewed automatically, plus the SAN certificate option is working as well.
We’ve published a video with instructions and demo here:
https://www.netometer.com/blog/?p=1758
Right now we are testing the client with Exchange server, and a video about this is coming as well.