Hi Philip Gross,
Thank you for posting in the Microsoft Community Forums.
When setting up Windows credentials for another system on your local area network (LAN) for folder/file sharing, you need to use a valid user name and password on the other system. Specifically, the following information should be used:
Username: This is a user account name on the target computer.
Password: This is the password for this user account.
Best regards
Neuvi Jiang