Problem

Cygwin does not have useradd or adduser. Instead, you should first create a user in Windows and run some commands in Cygwin to read the user list.

Create a Windows User

Create the user in Windows (Usually Start|Control Panel|Manage User Accounts|Add…)

Link to the Windows Users

Type mkpasswd -l > /etc/passwd and mkgroup -l > /etc/group to get all of the local users and group synced up. Otherwise, replace the -l with a -d to get all users and groups from the domain.