How do I grant permission to access Network - no user/password popup

I have one computer in my home network that I can not share files. I get the message below.
All of the other computer on my network would have a "popup box" where I would enter the Username and Password - but this one computer does not give me that popup.

Also I can access all of the other computer from this on ("GA-EG45M") but I can't access it from the others. Where do I go to authorize "access permissions"? All of the network discovery and sharing settings are set the same on all computers.

Checked this one yet? Logon failure: the user has not been granted the requested logon - Microsoft Community

Thanks for the Link.
I see that in the link they say to turn OFF "Password Protected Sharing" in "Advanced Sharing Settings". Mine has always been On (and it used to work). I'll try this when I get home tonight. I think switching my Win10 computer from a Local account to an MS account somehow caused this, as that is the only change made recently (although the issue is not on the Win10 machine).

There is also some info on checking the Group Policy Settings. I'll bet this is where my issue is.

I would add, try:
If it is enabled, disable Guest account
"Check Deny access to this computer from the network" setting in Group Policy (mine is set to Guest), same place as the one in the link.