Java Web Application -- 2

Servlet based web application is required following description.

Role based login system there are 5 roles i.e. SuperAdmin, Admin, Staff, Observer, and User.
Application caters to multiple clients each having its own admin, staff and users
SuperUser can has full control over all the clients. and observer has view rights only for all the clients or the clients selected by superadmin.
Admin has all the rights for a specific clients
Staff can make transactions.
users can just view data related to him.

We would like to store data related to user administration in one database and all the data related to client/s in their respective database. Database for client will have the tables as attached (id and timestamp fields are required to be added). Each client will have its own database which will be selected once users logs in. Super admin and observer the application should ask which client's data he wants to work with.

bidder is required to create crud application related to following three tables
mas This one is master table two of its fields (hd_code from mas_gl(gl_head) and post from mas_zone (post) )will be filled (fk) from following two tables.
form for data entry on mas table may look something similar to the screenshot attached.

I hope you have been through the description thoroughly.i want to add that database for user management is not in the description. Also the clients database is required for to be selected on the go. Super admin and observer will be presented with the list of databases where they can select any one.
Application needs to be ready for mobile app integration in future.

MVC based platform is preferred
application is required to be built with proper documentation/comments
please share previous experience and your plan to execute the task/assignment