In order to back up your rekordbox library follow these steps:
In My DJ Cloud, go to the "Library Backups" menu, and make sure that rekordbox is selected.
Open rekordbox and go to the file menu, then Library, then Backup Library.
Click Ok that it will take a long time.
IMPORTANT! When it asks to back up music files as well, you must select "NO"
IMPORTANT! When it asks where to save your backup, you must save it in your /Music/rekordbox-backups folder
Your backup will be created by rekordbox and automatically backed up in My DJ Cloud!
Since rekordbox backup creation is a manual process, you'll need to do these steps every time you want a new backup. Make sure to do it at least weekly!
You can view and download your backups from the My DJ Cloud app at any time.