Create an API from landing page to database

My business is a lab that runs several blood and health tests, including COVID-19 tests. We want to hand our patients a QR code that leads them to a landing page where they can insert their customer data and receive their results there. We already have a database set up and we have the endpoint where we have to connect to, but we need someone to develop the JavaScript code to insert in our Squarespace landing page in order to connect to the database. Attached is the data we received from the IT firm that works with us.