Hi! When Windows asks for Network credentials, it wants the username and password of an account on the desktop PC you’re trying to reach, the one that’s sharing the folder. If you sign in to that desktop with a Microsoft account, use the email address + Microsoft account password that you use to sign in the target device.
If you don’t want any password prompts, turn off “Password protected sharing” on the desktop in Control Panel > Network and Sharing Center > Advanced sharing settings > All Networks >Turn off password protected sharing