Hi,
Few questions:
1.) what kind of document will be uploaded by contributors?
2.) Users buyers are not allowed to view document uploaded by contributors before downloading it?
3.) Will it be free for contributors to get registered on your website?
I have reviewed the requirements and the provided google doc with functional requirements. In short what I understand is you want a website to be designed and developed where several contributors can register, login using social media logins as well, create and manage their profile, upload document with metadata like: document price/physical address associated with the document/description of the document (optional) and more. And, on the other hand, user can register, login using social media logins as well, search the property address, view the list of documents associate with the searched address and uploaded by various contributors, view live updates on the map as per the address selection, add required document to shopping cart and pay online. In addition, you want this application to be built with commission module or split payment system which will deduct the your % and send rest of the payment automatically to the contributors account.
We can build as we have already built application with all the features you have mentioned like: register, login with social media, download/upload file, add to cart, shopping cart, commission module or split payment system and more.
All we need answers of the requested ?s to move further