Copy files with elevated credentials in PowerShell - powershell

Question

Searched and searched, but cannot find an answer that works specifically for what I am looking for.
I want to call a PowerShell script from a logon vbscript that runs on logon. The PowerShell script will copy a file from a server network share to C:\Windows, but I need to embed credentials securely in the PowerShell script because the script will be hosted on a common share. I have already generated the AES key file and the password file I am decrypting with the AES key.
This is what I have so far
$User = "itadmin"
$source = "\\server\cip$\misc-programs\new_inb_install\inb.exe"
$destination = "C:\Windows\"
$PasswordFile = "\\server\cip$\misc-programs\new_inb_install\psw.txt"
$KeyFile = "\\server\cip$\misc-programs\new_inb_install\AES.key"
$key = Get-Content $KeyFile
$MyCredential = New-Object -TypeName System.Management.Automation.PSCredential `
-ArgumentList $User, (Get-Content $PasswordFile | ConvertTo-SecureString -key $key)
Copy-Item $source -Destination $destination -Recurse -Credential $MyCredential
The error I get when I run the code is
> Copy-Item : Cannot retrieve the dynamic parameters for the cmdlet. The FileSystem provider supports credentials only on the New-PSDrive
> cmdlet. Perform the operation again without
> specifying credentials.
> At line:12 char:1
> + Copy-Item $source -Destination $destination -Recurse -Credential $MyC ...
> + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + CategoryInfo : InvalidArgument: (:) [Copy-Item], ParentContainsErrorRecordException
> + FullyQualifiedErrorId : GetDynamicParametersException,Microsoft.PowerShell.Commands.CopyItemCommand
I should also mention, the credentials I am specifying I don't need for access to the server. I need to use those credentials to deal with UAC and make sure the end user isn't prompted for the service account creds.
Any help would be greatly appreciated!