How can I get the entire website when I have to login there to see the content?
I tried to use webhttrack but can't use it if the website requires a login with forms.
You can't really download a website. I don't know how http track or any other tools work , but typically a web site is made up of front end (HTML , JavaScript , CSS ) , a backend web server. Only the front end part of any website can be downloaded as you don't have access to machine running a web server.