Is it possible to download the protected part of the website (requires login) using WinHTTrack or some other tool and how? Best Regards
I don't know that tool but it would need to be able to log itself in You have to think, though, that the website owner doesn't want you doing that and maybe, just maybe, you should respect the owner and not try.
You can do this with wget, or via CURL (using PHP), but you will of course need an actual login to provide to the program. I'm assuming that if the program the OP mentions have any credibility whatsoever, it should be able to do this. And if you don't actually have a login for the parts you wish to download, you WILL be breaking some laws trying to get to the content. Depending on what country you're in, those laws might be minor, or major.
Of course I have login info. It's a plain membership website and I want to download Dashboard because of the design.
Well... you would be able to get the front-end of the dashboard - the HTML and the CSS and the javascript - you will not be able to download the backend (server-side) files, unless you have a login to the actual web-server. So, you can download the look, but the functionality won't come with it.