Is rekordbox 6 compatible with Engine DJ 2.0?

Yes. The XML export feature returned in rekordbox v6.3.0, allowing you to import your entire library into Engine DJ while maintaining playlist structure, hot cues, and loops. 

With Engine DJ v2.0, you can also select which type of cue you’d like to import — Memory Cues or Hot Cues. In addition, you can quickly import your entire collection tree by right-clicking on the rekordbox collection list, and choosing ‘Import Collection’.