Windows 10 network credentials?

The following I have 3 computers (1x PC and 2 notebooks), so the PC and 1 notebook runs via my Microsoft account, since they are my computers. And the 1 notebook runs on my dad, who had Windows 7 up to the present day. Since support for Windows 7 has now been discontinued, we have upgraded it to Windows 10.

So now to the real problem, I have an exchange drive on the PC so that I can play data from the notebook on the computer and vice versa. Now I wanted to integrate the old Windows 7 computer, since it now has Windows 10. However, now when I click on the notebook on the computer, the note appears: Please enter the login information. This notice also came under Windows 7. Yes, but I have no password only the user name. How can I get this password now? And that's another local account. The funny thing is on the notebook I don't see the computer, but the other way round I see the notebook on the computer.

Can someone help me there?

The whole connection happens via LAN cable. The network recognition (which you can see the computer) is active on all computers and all computers use a private network profile.

Here is the solution

https://www.drwindows.de/netzwerke/123952-netzwerk-verlangt-immer-passwort.html

Sorry but only helps a clean installation

No