icu4c-64_2-Win64-MSVC2017.zip cannot be unpacked by cygwin unzip
Unzipping that zipfile kind of succeeds, but unzip outputs:
warning: icu4c-64_2-Win64-MSVC2017.zip appears to use backslashes as path separators
This causes unzip to abort. While it's possible to work around, it requires some contortions
if your unzipper is buried in some standard download script.
You're probably using PowerShell to build the zipfile. Others have run into this bug, and even reported it to Microsoft along with a fix:
Others have just given up on using powershell to create zipfiles. Your call. Whichever you do, please arrange to output legal .zip files. Thanks!