SOLUTION:
As Kareem pointed out, there were two issues with my code.
Using a system call in my code: `system("clear");
- Removed this line completely. Probably an issue with server rights.
Excluding 0 as a valid user input. My code simply didn't follow all of the instructions.
- Removed the "=" in the line
} while((num <= 0)||(num > 23));
Once both were resolved, check50 returned all green happy faces :)