The project triggers an error when cloning on Windows when using Git 2.24 or higher:
filename in tree entry contains backslash: '\'

• Potential offending commit in civetweb: 4ac467e
• Offending commit in Git 2.24: git/git@e1d911d
• Git for Windows issue: Git 2.24 breaks existing repositories: filename in tree entry contains backslash git-for-windows/git#2435

Workaround

Disable core.protectNTFS:
git config --global core.protectNTFS false

Additional details can be found here:
zephyrproject-rtos/zephyr#21426