have a quick look to full guide - Under "Chapter: Installing the Plug-in and Registering the UCS Domains"
**Plug-in package hosted on HTTP or HTTPS server. Ensure that the HTTP or HTTPS URL of the plug-in zip file is reachable from both vCenter server and the machine from which the plug-in is registered**
any linux or win running http/https services wold work.
Regards,
MJ