For someone reading your message and perhaps be able to help you, you would
need to provide helpful information, so helpers can get a better picture.
Right now, there is zero information, and this is impossible for anyone here
on the forum to even start thinking about it.

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HINT: READ THIS FIRST!
DO NEVER provide any confidential information in here, in particular personal
credentials such as username and password!
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What people here need to have is at minimum the URL (the web address) you are
talking about, so someone may take a first look and get an idea.

Also it would be good to know which operating system you are planning to use
to utilize HTTrack. Mac? Linux? Windows?
And it would be good to get confirmed, that you have been able to access this
website with your own credentials (AGAIN: DO NOT provide this actual
credentials) so far.