MySQL (modify existing DB) & JSON (modify existing API)

Please contact with questions related to project only. Overview: The DB functions as a backend for an iOS app which uses a custom API to read/write info to a MySQL database/webapp on AWS. The app which is a fitness tracker allows both trainers and clients to track their progress. Currently the db/tables are functioning for the trainers. They are able to view complete programs that are uploaded through the web app onto the iOS app via the API. This job entails the second half in which the tables you will create will allow a client to record their workout information (ex: time, sets, reps, weights) to the database. That information will be readable by the trainer. You should be familiar with membership based websites and have a strong knowledge of relational databases. Provided: GIT Invite to Repo Php/MyAdmin Access JSON:
After creating the MySQL tables, add ability to read/write data to API. The API functions currently and any work you do will be added to the existing API using JSON. Time of Completion & Milestones TOC: 3 Days Milestones- READ CAREFULLY

Milestones will be paid as follows: 60% Create the job as described using the existing PHPMyAdmin site & creation of the API 40% confirmed testing of the API and the ability to successfully record data to the created database/tables by the developer through testing. Note: ***THE SECOND MILESTONE MAY TAKE UP TO 5 DAYS BEFORE IT IS RELEASED. SUCCESSFUL TESTING MUST BE CONFIRMED (BY DEV) UNLESS CHANGES NEED TO BE MADE TO THE TABLE STRUCTURE THROUGH DEVELOPER REQUIREMENT.