I've bought a dd.-800 , rekordbox doesn't allow me import tracks

i've been using serato dj , now i bought dd.-800 i would like to use record box , but for some reason i can't use the video music i already have in my external memory,

i Already create a new crates ( play list in record box) , i was able to import all the music i already have in my MAC , however i can not import to those playlist the music i have in my external memory ( more than i have in my MAC )

I try to storage  all the music and video music in this external memory , with serato i dont have this problem , i can storage any video music in any external memory , then i can import to any crate ,with out problem , when i use the MAc for work , i dont need those music storage in my MAC in order to dont consume memory 

the only way i can use the music storage in that memory is creating a folders in the external memory , and use them in rekordbox , really i dont like it beacuse there are music that are old fassion , that is why i created a new playlist in record box , so i can use just the music i want , not all of them