Hello Luis,
WSS Agent is only supported on Windows 10+ and macOS Mojave+ operating systems. It is designed as an endpoint solution for Web Security Service. UA and WSSA are not officially supported for Windows Server. It may be possible to protect the traffic from those servers using another access method, such as explicit proxy (PAC file), or sending the traffic through an IPSEC tunnel (I would only recommend this if you already have this connection set up). However, these are not officially supported methods for protecting Server traffic.
Requirements and OSs supported by WSSA:
https://portal.threatpulse.com/docs/sol/ReleaseNotes/RN_UA_fixes.htmWSS Access Methods:
http://portal.threatpulse.com/docs/am/connectivity/fixed/conn-fixed-select.htmExplicit Proxy Access Method:
http://portal.threatpulse.com/docs/am/connectivity/endpoint/explicit/conn-about-explicit.htm