How to download all your purchased Instrumental tracks, and other keys?

Just follow the next steps:

1- Log in  (sign in) 

2- On the Bottom in the middle column you will see, "Service: My Account"
(Just  click there)

3- There you have access to all  your purchased files.
Click on  i (the small letter next to the price of the Instrumental Track you bought).

You will arrive at the Download page.