You have to design the front end in php as per the file protocol-front-end file and backend in mysql as per the database diagram attached in the screenshot file protocol-backend file.
The Basic functionalities will be as follows:
Admin will do the entry in the front end as per the design file, create users etc, Old entries must not be replaced. Any changes should be logged as per datetime and user.
User can be able to see / view the records as per the design file.
Once the quotation is selected I will share the data on private message.
Please quote properly as this is just one module (Billing... there will be more modules like same in near future)
Payment will be done per modules.