I know it is now too late.

However, as a tip for next time: 
provide all helpful information possible (excluding of course credentials
etc.). So that someone may be able to inspect whatever is possible by looking
at the publicly accessible part of the website. Perhaps someone already
identifies by the name of the website already what the issue is from past
experience. As it might be that content download is driven by JavaScript, or
additional obfuscation in delivery (especially for content the website owner
does not offer actually for download intention), which adds complexity and is
usually not possible / not that easy to capture.
An pseudo URL such as "Access.XYZ.de" is not helpful. There is no "one recipe"
to download a website. It always depends how it was built.