usually studying is done after school at a university
If you have left school and started studying.
The most important thing to learn is to become independent of the professors "teaching" which is often not teaching but read out.
The basic thing is to learn how to do independent completion of projects.
This includes asking experts (other experts than the professors)
You seem to have underestimated how much time it needs to learn programming
or other possability you have been lazy about working on this project.
Your code needs to count-down until the button is pressed.
Then the count-down shall stop and the buzzer shall be turned on
which means change from executing count-down to execute buzzing.
Be the change you want to see in the world
best regards Stefan