Collaborative Working/ Document Control - Platform/ Website

General information for the website: Contract and Communication Management Website
Description of requirements/features: I need a website/ online platform to allow multiple members/ teams to collaborate and share documents, with strict privacy controls and membership levels.

Access levels/ membership types:

Site administrator(s);
Client member(s)/ team of users;
Contractor member(s)/ team of users;
Supplier member(s)/ team of users;

Requirement for members/ team - to be configured by site administrator:

1 Client member/ team;
Multiple Contractor members as needed/ multiple teams (separate entities from each other);
Multiple Supplier members as needed/ multiple teams (separate entities from each other);

Privacy controls (configured by site administrator) must be in place to only allow the sharing of documents and messages between Client/ Contractor(s)/ Supplier(s) as configured.
The site will facilitate the sending/ sharing of private legal documents and various forms of messages/ formal submissions to each other.
The documents/ messages/ submissions will be time-sensitive, therefore should include a separate dashboard and notification system for each user/ team.
Documents will be either 'acknowledged' (submitted/ received/ marked as read) then either 'accepted' (agree to the document content/ e-signature) or 'rejected' (disagree to the document content/ e-signature still required).
Extra services needed: Installation, Customization, Optimization, Security
Similar urls: http://cemar.co.uk/overview
Extra notes: Further information will be sent to those who can demonstrate their ability to take on this project.
This is likely to be an ongoing project for right person - no development teams please, individuals only.

Please state which technologies you would build this project with, including reasons for choice.

Many thanks,
Richard