Build App with Database backend and workflows to trigger emails

I have built a prototype of a app to collect visitor data. Including workflows for alerts where certain threads holds are triggered within SmartSheet. Using a web based form end users complete a selection of questions, additional questions may appear based on previous responses. Data is then collected in SmartSheet. Looking for someone to build outside of SmartSheet so that I can host and provide app to my customers. This will require components for Staff (who are setup as users and login and details against a staff table), visitors and contractors who will need to provide more information such as Name, Company, phone number plus optionally email address. As well for Visitors/Contractors to select from a drop down the staff member they are visiting which will look back to the "staff table". The staff member being visited will get a push notification of all the details entered to make an assessment if they proceed to meet the person. Anyone who is outside the threshold in relation to symptoms / temperature will need to receive an instant alert to leave the office and contact there direct manager. the direct manager should be notified of this via push notification through the app. When a visitor, staff member or contractor leaves they have the ability to checkout. Additionally there should be capacity for admin user > full access, department user > can modify staff table and end user > data entry only. For visitors and contractors they shall not need to sign in.