PowerShell DSC Group Resource - "Could not find a principal with the provided name"

You have to specify the credentials:

Example:

Way to get the credentials:

$securedstring = ConvertTo-SecureString -String $Password -AsPlainText -Force
[PSCredential]$cred = New-Object System.Management.Automation.PSCredential ($UserName, $securedstring)

And this is the code u need to configure the DSC resource

$ConfigurationData = @{
    AllNodes = @(
        @{
            NodeName="*"
            PSDscAllowPlainTextPassword=$true
         }
        @{
            NodeName="SRV2-WS2012R2"
         }
        @{
            NodeName="SRV3-WS2012R2"
         }
   )
}


Node $AllNodes.NodeName
{
    LocalConfigurationManager
    {
        RebootNodeIfNeeded = $false
    }

    Group $group.Name
    {
        GroupName = $group.Name
        Ensure = $group.Ensure
        Members = $group.Members
        Credential = $cred
    }
}

Then simply execute

ProcessDscResources -ConfigurationData $ConfigurationData -OutputPath $folderPathTmp

Start-DscConfiguration -Wait -Force -Path $folderPathTmp