Exit Cloud Library Sync

Hello Community

I started using the cloud sync feature with Dropbox a while ago. Now I want to stop using it again for various reasons, but first and foremost I find the function too dangerous because it has happened time and again that tracks were not downloaded before they were exported to the USB stick, which I only noticed in the club. I also want to cancel my Dropbox account as I no longer need it except for Rekordbox. 

This means I want to move all my tracks to local storage or to an external hard disk where all my music is stored. However, when I try to move the synchronized playlists back to the local storage, I always get the message that there is not enough space. I have tried various folders, including local ones, because I thought that maybe it just doesn't work with the external hard disk, but the message appears in every situation. 

Does anyone know either where the error message comes from, or even better, if there is a way to simply say I don't want to synchronize anymore, download all data not on the local storage?

Many thanks for your help!

Best regards