It’s documented in the code
// see for explanation: https://github.com/JChristensen/DS3232RTC#alarm-methods
RTC.setAlarm(ALM1_MATCH_SECONDS, 30, 00, 0, 0); //set your wake-up time here:
RTC.setAlarm(ALM2_MATCH_MINUTES, 0, 10, 0, 0); //where "xx" is minutes
// every 00 minutes past the hour;
// if every minute is needed change MINUTES to SECONDS (only for ALM1)
// matches seconds AND minutes when _MINUTES is used. Sequence of time:
// first seconds, then minutes, hours, daydate
// or: seconds (but enter 00, is ignored), minutes then hours, daydate for ALM2
// zero's mean: always
// example: Set alarm1 every day at 18:33
// RTC.setAlarm(ALM1_MATCH_HOURS, 33, 18, 0); set your wake-up time here
// RTC.alarmInterrupt(1, true);