For those using Chocolatey
(this is not published on the website yet, but found the info in the github repo):
Watchman is available to install via the Chocolatey Windows package manager. Installation is as simple as:
PS C:\> choco install watchman
Reference: https://github.com/facebook/watchman/blob/573b18b86b88759f31e83fa2e1837539d138de22/website/_docs/install.markdown#installing-on-windows-via-chocolatey
Beware that installing Chocolatey itself is somewhat tedious, but here is the link if you’d like to give it a go:
https://chocolatey.org/courses/installation