The username which you need to provide is the one that you had registered at the Git Winch coordination server. But please note: Git Winch can be privately hosted too. In order to check the coordination server that particular Git Winch is connected to, open the file gitwinch.ini in the application folder and check this entry:
SystemAPIurl=<url>
Extract the domain name from the value for the <url> indicated after the equals-to sign. That would be the website where you have to register and get your username.
If you are not using a privately hosted Git Winch, follow the registration link at our main website: https://gitwinch.com You can easily get a free registration into our own common coordination server. (It is a pay-as-you-go system. You get some initial credits free for you to try it out)