How to find delta file names from two tags in Azure repo

I am trying to use the pasted code..

Code:-

$targetfolder = "$(Build.StagingDirectory)" + "/"

function CopyFiles{
param( [string]$source )

$target = $targetfolder + $source

New-Item -Force $target
copy-item $source $target -Force

}

$changes = git diff --name-only --relative --diff-filter AMR HEAD^ HEAD .

if ($changes -is [string]){ CopyFiles $changes }
else
{
if ($changes -is [array])
{
foreach ($change in $changes){ CopyFiles $change }
}
}

This script will it execute in Azure Repo