1/ Go to ARR Cache, then Server Proxy Settings
2/ Check on Enable proxy
3/ Create a site call AutoACME and add a binding to support autoacme.com port 80
4/ Go to URL Rewrite
5/ Add a blank rule under Inbound and put Pattern = .well-known/acme-challenge/(.*)
Rewrite URL = http://autoacme.com/{R:1}
6/ In hosts file, add autoacme.com to point to IP of current server
7/ Add a file into folder of AutoACME site and it
8/ Go to Centralized Certificates / Edit Feature Settings
9/ Config it, points to a localtion which will be used by AutoACME + the CPKP password which AutoACME will encrypt