Assuming it is not an OS compatibility issue (which it may well be), you would not be able to activate it anyway. The activation servers for CS2 and earlier are dead and gone.
See the page in the link below. Follow the directions carefully. And see if that works for you.
Which version of mac os x?
If it's anything newer than os x 10.6.8 snow leopard, then photoshop cs2 will not work on your Macbook Air.