As I stated in the question, I cannot figure out which debugger to download from here.
All I could find was this:
Go to the Apple Menu and select “About this Mac”. If you have a Core Duo processor, you have a 32-bit CPU. Otherwise (Core 2 Duo, Xeon, i3, i5, i7, anything else), you have a 64-bit CPU.
Here are the specs of the macbook.
Thanks in advance.