Hi, Group!  I need to build a solution for the following use case, and I'm not sure of the best way to go.  I'd appreciate any advice and suggestions you might have:

• My client wants to enable secure file exchange, navigation, management and approval for each of their customers via a Community;
• They want each of their customers to be able to upload individual files or "bundles" of files and place them within a familiar folder-like structure.  When new files are uploaded, the appropriate employee(s) of my client should be notified.
• They want employees to be able to upload files for customers to approve and download.  When an employee posts a new file or a group of files, the customer should be notified.
• Customers should be able to approve and reject files either individually or as a group/folder, with comments. Appropriate employees should be notified on approval/rejection.
• Naturally, each customer should only be able to see their own files.

Ideally, I'd like to be able to do all this with Salesforce, but I'm open to integrating Box or another partner document management platform.  I've never created anything like this before, and currently I'm stuck.  Again, I'd greatly appreciate any suggestions you may have.  Thanks!