Sync library from computer to mobile phone app

I am on the creative plan, and my goal is mainly to be able to listen to my Rekordbox library (that is on my home computer) on my mobile phone, so I can listen to those tracks while in the car or working out. But when on the mobile app it appears to only detect the tracks, but they remain grayed out and unselectable.

I just downloaded the DropBox desktop app onto my computer, and that has not solved the problem.

Any assistance to get this working would be much appreciated.

Thanks!

Tony