I would like to use the DS3231 rtc module as timer and the attiny as the microcontroller. Do I need to add additional components such as resistors, capacitors and crystal?

 

hi GC,
The DS3231 module has its own crystal and 3v back up battery on its PCB.
You need two 2k2 pull up resistors to Vcc, one for the SDA and one for the SCL lines.

E