The first release does depend on IIS 6 Management Compatability --> IIS 6 Scripting Tools.

This has already been changed in the source that it no longer depends on iis 6 scripting tools compatability but it was part of the first release of 1.3.0.

I have configured your steps but I cannot install free SSL cert successfully.

When I click on install free certificate, the message is "Lets Encrypt Installed" but the cert is not installed.

Apllication log error on Windows Server 2012 with IIS 8:

Log Name: Application
Source: letsencrypt_win_simple
Date: 10/10/2017 11:24:47 AM
Event ID: 20464
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: ***
Description:
Exception "Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information."

I am using a website with dedicated IP.

Ah.

Website with dedicated IP requires an additional fix which i am still testing.

I hope to finish that within the next 48 hours

Do you fix this issue?

I haven't verified it yet (i got out sick for quite a bit).

I do think one of the fixes in the SolidCP Server should of worked in this situation too.

I will have to check and verify it yet though (you can also try updating the SolidCP server with current files and see if it works).