A Network Computer will not accept credenials

I have a private wireless network with three computers all running Windows 10. Two use the same Microsoft account and the third uses a different one but they all show up in File Explorer on the first two. But when I try to open the third one I get a request for credentials. I fill in the window with the name and password for third one but it is not accepted. I'm sure what I entered is correct for that machine. Is there something I need to do on that machine to get what I believe to be the correct credentials accepted?

Thank you?

BTW, the third machine can open the two other machines and show the shared files on them.

You are entering a username and password for an administrative user on the PC your connecting to not your own pc one?

Samuria said:

You are entering a username and password for an administrative user on the PC your connecting to not your own pc one?

Yes, that is correct.
Thank you

Have you setup a share on the pc and how are you connectin ie map drive, explorer

Samuria said:

Have you setup a share on the pc and how are you connectin ie map drive, explorer

Yes, Thank you.