What does a Windows managed host need so that Ansible can manage it?

PowerShell 3.0 or later (current Ansible releases require 5.1), PowerShell remoting configured (WinRM), and .NET Framework 4.0 or later. Python is not needed.

Windows modules (listed in the Windows section of the Ansible module index, e.g. win_package, win_service) are written in PowerShell, not Python. So a Windows host needs:

• PowerShell 3.0+, which runs the modules. That is the classic minimum; current Ansible releases require PowerShell 5.1, which means Windows Server 2016 / Windows 10 or later;
• Windows PowerShell remoting configured, which is how the control node connects (WinRM);
• .NET Framework 4.0+.

The control node itself still runs on Linux. Ansible manages Windows hosts remotely, but you can't use a Windows machine as the control node.

Go deeper:

• Managing Windows hosts with Ansible (official docs) — current host requirements and the WinRM, PSRP and SSH connection options.
• Windows Remote Management (official docs) — setting up WinRM listeners, authentication and encryption, plus troubleshooting.