best file management / download manager plugin?

Hi,

I’m using word press v3.6.1 and wondered if anyone can recommend a good plugin that specifically allows me to:

– assign users to ‘groups’
– setup download areas / file manager tree where certain files and folders will only be visible to certain users or groups of users

There are loads of user cases for this, e.g. a Dr who wants to upload patient files and when a patient logs in, they can only see files linked to their user account. Or a Landlord who wants to upload tenancy details and property documents that relate to a specific property, and when a user (tenant) logs in, they can only view files associated to the property they live in etc.

I can’t seem to find a plugin for wordpress that caters for this, even though it seems like a fundamental plugin with lots of potential usecases.

Any recommendations would be great!

Thanks in advance