$ConfigData = @{
    AllNodes = @(
        @{
            NodeName = 'hostname'
            CertificateFile = '/tmp/certificates/hostname.cer'
            Thumbprint = '3A9016961C4650036E298DE4AA0D3BE1054B9610'
        }
    )
}

Configuration CredsRequired {
    Import-DscResource -ModuleName PSDscResources

    $myPassword = 'password' | ConvertTo-SecureString -AsPlainText -Force
    $myCredential = [System.Management.Automation.PSCredential]::New('myUser', $myPassword)

    Node $AllNodes.NodeName {
        Group Administrators {
            GroupName        = 'Administrators'
            MembersToInclude = 'myGroup'
            Credential       = $myCredential
        }
    }
}

& CredsRequired -ConfigurationData $ConfigData

Write-Error: /opt/microsoft/powershell/7-preview/Modules/PSDesiredStateConfiguration/PSDesiredStateConfiguration.psm1:317
Line |
 317 |              ConvertTo-MOFInstance MSFT_Credential $newValue
     |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     | System.Management.Automation.CommandNotFoundException error processing property 'Password' OF TYPE 'MSFT_Credential': The term
     | 'Protect-CmsMessage' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the
     | name, or if a path was included, verify that the path is correct and try again.

Write-Error: /opt/microsoft/powershell/7-preview/Modules/PSDesiredStateConfiguration/PSDesiredStateConfiguration.psm1:2307
Line |
2307 |  …             Write-NodeMOFFile $Name $mofNode $Script:NodeInstanceAlia …
     |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     | Invalid MOF definition for node 'hostname': Exception calling "ValidateInstanceText" with "1" argument(s): "Value cannot
     | be null."



    Directory: /tmp/CredsRequired

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-----          01/22/2020    12:16           1090 hostname.mof.error
InvalidOperation: /opt/microsoft/powershell/7-preview/Modules/PSDesiredStateConfiguration/PSDesiredStateConfiguration.psm1:3745
Line |
3745 |      throw $ErrorRecord
     |      ~~~~~~~~~~~~~~~~~~
     | Errors occurred while processing configuration 'CredsRequired'.