Connect an existing Laravel backend to a Flutter Frontend

We have an existing Laravel/MySQL backend to an existing Flutter frontend.
See Demo Access Below:
​ Frontend: https://script.viserlab.com/viserhotel/
Admin Access: https://script.viserlab.com/viserhotel/admin
Receptionist Access: https://script.viserlab.com/viserhotel/receptionist

​ Admin Login: Username: admin | Password: admin
Receptionist Login: Username: receptionist | Password: receptionist