I'm not sure about Rekordbox and how it imports files, but if you want to drag files into subfolders in a folder on the desktop, and then have automator move them to corresponding subfolders in the Collection folder, that would be pretty simple:
set up the desktop folder and its subfolders.
open Automator and create a new Folder action
specify the first source subfolder at the top
add "Move finder items" from the list of actions on the left, and specify the destination subfolder
save this first Folder action and give it a name.
You would create a separate folder action for for each source and destination subfolder pair.
Sometimes it seems overwhelming but just just picture Automator as a recorder that will will record all of your actions or key strokes then play them back when you tell it to.
Look here and learn.....
Thanks arthur i diddn't tought it was that easy.
i tried to record it but i could only move one song from folder to folder and import to rekordbox so it would only record the name of one file and not a complete folder because osx overwrites a folder and doesn't add only the new files but thanks anyway!