@MDtar7 Im running out of ideas, but try enabling SMB 1.0 support on your PC.
Its in Control Panel, Programs and Features, Turn Windows Feature On or Off and select SMB 1.0/CIFS File Sharing Support. Restart your computer and try it again.
Screenshot from 2020-03-26 12-21-15.png
Thre is not root password in the RetroPie image for the PI. The pi user has sudo privileges, so no password is needed if you prefix your commands with sudo.
What is the command/action you're trying to acomplish ? Move a file, edit a file, run a comand, etc. ?
I had the same error once on a fresh install with one of the carbon theme files. Like I said it was a fresh install and i never touched the file. I ignored it and i believe it was mentioned by someone else here. Deleting and reinstalling carbon fixed it. But yeah i think sometimes git has this issue.