Windows 10 PC can't see other shares in Workgroup

We set up our small business network as a Workgroup awhile ago with all Windows XP computers. Some have been since upgraded to Windows 7, others to Windows 10. The most important issue is a folder on an XP machine that all others in the network need to be able to access.

We just installed a new Windows 10 PC. I joined the workgroup, but not all the PCs in the workgroup show up in File Explorer (in particular, the one I need is not there). I tried mapping a drive letter to the share, but the login screen is confusing, asking for an email address and PIN (I've never seen or used anything like this, always logged on via account on the target computer).

So I click "More Choices", where it allows me to put in the userid and password of the matching account on the target XP box, but it just returns me to the "email/pin" screen with a cryptic message:

"A specified login session does not exist. It may already have been terminated."

Help...

PS, I am able to ping the target computer

I managed to disable PIN login (the tutorial here didn't quite fit, there is no "remove" option on my screen - I must have a new version of Win10?). Anyway, now it asks for ID/Password as expected, but still the same error message.

I notice that for all other computers on the network, the userID is the same as the ComputerName. - Is that important?

I disabled PIN login, and changed my computer name to match the login ID. Now I can map and access the folder I need (though I still can't "see" it under networks in file explorer, but the target computer CAN see this one...)

However, now every time I re-boot I get a screen prompting me to re-enable PIN login, with a message
"Your organization requires Windows Hello"

the screen offers NO OPTION to bypass or decline setting up a pin. I can click the button, which brings me to an online login screen, where, after logging in with an authorization code, I can click cancel and proceed (after another warning) without setting up a PIN.

So I tried re-enabling the PIN option to see if it would "remember" how to log into the network share. It worked once, then failed after the next reboot.

Is there a way to PERMANENTLY disable "Windows Hello" (whatever the heck that is) so Windows will stop hassling me to enable PIN?

Okay, I've learned that the person who installed this computer chose the "My Organization" option rather than "I Own It". This, I think, means logging into a domain (which we don't have). My guess is this is the source of the "Your organization requires Windows Hello" message.

Is there a way to undo this setup choice?

I fixed a similar problem last week by assigning a fixed IP address to each PC in the router. You also need to set the sharing and security permissions to Everyone for the shared folders and ensure file & printer sharing is on with no password for access.

Figured it out.

I used the Group Policy Editor to disable "Windows Hello".

I'd never touched Group Policy before, and don't really understand what it is, but it worked.

Can't remember now where I found the instructions, but there are sinister ones here:
How to disable Microsoft Windows Hello for Business on Windows 10 machine without purchasing Microsoft Intune : MOST