I found a solution from youtuber DIY PC HELP: "Windows 11 Remote Desktop Credentials Not Working!".
- Open "Credential Manager" (Start, "Credential Manager").
- Select "Windows Credentials".
- Third section, "Generic Credentials", find "MicrosoftAccount:user=USERID".
- Expand, Edit, and then enter your Microsoft Account password. You'll then be able to use this from your RDP client.