Help with a requirement

Hi All,
I have a requirement but cannot seem to find the correct combination of plugins/tools to use.
I would like a website to have a client login which takes them to a document library where we can dump files for them to collect.
Each client would have their own login and go to a different location for their documents.

So, customer A logs in and see their documents, customer B logs in and sees their documents, they cannot see each others documents.

I have installed the members plugin but it looks like i can only assign permissions to a page by a generic group rather than on a user by user basis.

Has anyone achieved what i need? If so how?

Thanks!