powershell one liner to download file with credentials

I am currently trying to instruct a newly created windows shell to download a powershell script via autounattend.xml file. With that technique, i need a one liner to get the job done.

I used to be able to download them from a public environment using this one-liner :

<Path>powershell -NoLogo -Command "((new-object System.Net.WebClient).DownloadFile('https://some.remote.public.location/myfile.ps1', 'c:\Windows\Temp\myfile.ps1')"</Path>

But now i need to give in proper credentials to download my file from a private location. I tried the following and it doesn't work :

<Path>powershell -NoLogo -Command "((new-object System.Net.WebClient).Credentials = new-object System.Net.NetworkCredential("user123", "password123")).DownloadFile('https://some.remote.private.location/myfile.ps1', 'c:\Windows\Temp\myfile.ps1')"</Path>

(I'm a rookie in powershell :/)

How can i give the proper credentials to the DownloadFile Method in a one liner?

Or is there another command better suited for the job?

Thanks.