Automatic appointment import in calendar

Does anyone have an idea: I would like to export the duty roster of our company in such a way that each employee is saved an appointment file in an NC folder, which is then automatically read or imported by the NC calendar and each employee can then see their own duty roster in the calendar on their smartphone. Does anyone have an idea whether or how this can be implemented?
Our duty roster programme can save all the duties of an employee in an ics file, but the NC calendar cannot read in an ics file with multiple appointments.
Or in which file format would the respective duty roster have to be exported?

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