Server 2012 R2 – hidden Share$ not accessible

I just ran into this exact situation:

We found that the issue was caused due to a number of file system and registry permissions settings defined in the Default Domain Controllers Policy. While no one can seem to explain why these settings were in that GPO, this does help explain why a 2012 R2 member server would run just fine; but begin to have issues after being promoted. We ended up having to reset this policy to defaults (with the help of MS Support). It took quite a bit of time to get reg key & directory permissions back to the point where all of the services would start. – Cybersylum Jun 23 '14 at 11:38

I'm assuming, since you say the server is prompting for passwords and because the server is in a domain that the users in question are not part of the domain.

If the users are part of the domain, look at the NTFS file permissions inside the share and make sure that everyone you want to have access does, in fact, have access. You have to set the permissions at both the file/NTFS level and the share level.

If you want users who aren't part of the domain to access the share without passwords, "Guest" is the account users connect as if they don't have an account on the server. To quote MSDN:

People who do not have an actual account in the domain can use the Guest account. A user whose account is disabled (but not deleted) can also use the Guest account. The Guest account does not require a password.

You can set rights and permissions for the Guest account just like any user account. By default, the Guest account is a member of the built-in Guests group and the Domain Guests global group, which allows a user to log on to a domain. The Guest account is disabled by default, and we recommend that it stay disabled.

In other words, if the users are not a part of the domain, your statements "We have one folder on a Windows Server 2012 R2 that we want to share without passwords" and "I also don't want to enable a guest account" are mutually exclusive.