I'd start over. Go to 'Computer Management' and 'Shared Folder.' Make note of any folders being shared that don't end with a '$' and unshare them. Make your way to your 'Windows Defender Firewall' and restore defaults. Now bring up 'Credentials Manager' and remove any Windows Credentials you may have used when sharing files.
Off two computers that want to read/write the share, go to File Explorer and expand the Network folder. It'll tell you to turn on 'network sharing' if your network is not set to 'private.' It can take MINUTES for other computers to show. Remember do that off those two computers.
At the same time while Windows looks for the computers, you can right click the folder you want to share and give access to the appropriate accounts. If you don't want to use username/password, then choose homegroup.
If by then computers have yet to show, you can press F5 to refresh the Network screen or just forcibly view it via \\COMPUTERNAME\ in windows explorer. If nothing happens, ping it. If you can't ping it, then you know you what's up.