I need a responsive web app, which does 3 tasks:
1. embed an existing web messenger (which is also available as an iOS and Android app) like "[url removed, login to view]"
2. calendar booking/appointment
Admin can define users.
Users can log into the system and
1. write & read messages (via messenger, but embedded)
2. book available slots in the calendar
3. download+upload files
See attached files.