That looks like an improvement!
You might also have to create a web.config file at C:\inetpub\wwwroot\easyinstallmdm\.well-known\acme-challenge\web.config to allow extensionless files in IIS:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<staticContent>
<mimeMap fileExtension=".*" mimeType="text/plain" />
</staticContent>
</system.webServer>
</configuration>