Physiotherapy practice in the process of being established seeks practice software

I am looking for practice management software for a newly established physiotherapy practice in northern Germany (several therapists, 4 rooms).

The solution should meet the following requirements:

• Appointment scheduling (for multiple therapists)
• Patient data entry
• It would also be very practical to have the option of scanning and checking prescriptions
• Invoice writing
• External access, e.g., to be able to enter appointments from home (suitable for home office)
• App for managing the schedule
• Backup creation
• The ability to use the software before the practice opens on June 1, 2018, in order to already have appointments for the start
• Above all, Windows-compatible (computer)
• Android-compatible (mobile phone)

A desktop PC (MS Windows) and possibly a laptop (Mac OS) are planned for workstations.