Digital alarm clock

If the serial monitor showed nothing, you also have a problem with the code.

Something like this would work.
https://www.jameco.com/z/AZ-1440E-P-LF-Kobitone-Audio-Company-Buzzer-Piezo-5-Vp-p-80-dB-4-kHz-5-mA-Pin-Contacts_2098523.html

However you can drive your buzzer with a transistor cct.