Seems simple if you know how. It's not exactly the same but very similar. You can use a Powershell Script to get ride of the "download-" part.
# Root path
$RootPath = "C:\Temp\"
# Rename folders
Get-ChildItem -Path $RootPath -Filter 'download -*' | Rename-Item -NewName { $_.Name -replace 'download -*', '' }
How it works is $RootPath defines your File location. In your case it would be something like: "C:\Users\Username\Downloads"
Next Get-ChildItem looks for a file with "download -" at the beginning of the filename and replaces it with nothing. In other words it removes that part.
Here is the previous post I based the script on.
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