Powershell error loading dlls

I have a powershell script where I load some sharepoint assemblies. It works on my machine but when I zip it up with the dlls and send it to my friend. He puts the dlls in the correct place and then runs the script and we get this error:

cmdlet Get-Credential at command pipeline position 1
Supply values for the following parameters:
Credential
Could not load file or assembly '<file:///C:\Program Files\Common Files\Microsoft>
 Shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.dll' or one o
f its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131
515)

We have the same version of powershell

add the dlls like so

Try{
    Add-Type -Path 'C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.dll'
    Add-Type -Path 'C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.Runtime.dll'
    Add-Type -Path 'C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.Publishing.dll'
    Add-Type -Path 'C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.Taxonomy.dll'
}

catch {
                    Write-Host $_.Exception.Message
                Write-Host "No further parts of the migration will be completed, The script will now exit" 
                Exit
}