Energy Set Builder expects two exports from the same Rekordbox playlist: one Text export and one M3U8 export. The Text file preserves playlist details; the M3U8 file preserves the pathing needed for a clean reimport workflow.
Use one working playlist, not two different crates or collection views. Both exported files should describe the same source playlist.
In Rekordbox, right-click the playlist and choose the Text export option. Save it somewhere easy to find.
Right-click the same playlist again, choose the playlist export option, and save it in M3U8 format.
Use the TXT upload area for the Text export and the M3U8 upload area for the playlist export. If one file comes from a different playlist, the output will not reflect the set you meant to build.
Once both files are exported, upload them into Energy Set Builder, choose Split or Extract mode, set your constraints, then download the generated playlists and import them back into Rekordbox.
Start on the free plan — no credit card required. Verify the output, then upgrade only when you need more.