Solco brings over the work you did in another app: playlists and folders, hot cues, memory cues, loops, ratings and colours. It never adds, moves or retags files, and it only reads the other app's library.
First, add your music folders
An import attaches to tracks Solco has already scanned. Add the folders that hold your music first (see "Getting started with Solco"), then import. Tracks match by file location, even from an export made on another computer whose music lives under a different folder.
Import
Open Settings › Library and find Import from other apps. On a computer that runs the other app there is nothing to export first.
rekordbox. On a Mac or PC with rekordbox 6 or 7, Import… reads rekordbox's own library. rekordbox can stay open: Solco reads a copy and never changes rekordbox's files. Elsewhere, or if that read fails, use File › Export Collection in xml format in rekordbox, then Choose XML… in Solco. Intelligent playlists are rules, so the direct read skips them; the XML export brings their current tracks as ordinary playlists.
Traktor. Import… reads collection.nml from the newest Traktor folder in Documents/Native Instruments. For another collection, such as one copied from another computer, use Choose file…. Smartlists, grid markers and Traktor's _LOOPS and _RECORDINGS lists are skipped.
Apple Music. On a Mac, Import… reads the Music app's library directly; macOS asks once to allow access. If you said no, allow it under System Settings › Privacy & Security › Media & Apple Music, or export the library in the Music app (File › Library › Export Library) and use Choose Library.xml…. On Windows and Linux, choose an exported Library.xml with Choose file…. Apple Music brings your own playlists, folders and ratings. Smart playlists, protected purchases (.m4p) and streaming-only tracks are left out.
You can also drop any of these export files on Solco's window.
Review before anything changes
Nothing is written until you confirm. The review says how many tracks matched and why others did not, which playlists are new or updated, how many cues, ratings and colours are added, and what is not imported. Files outside your music folders are listed with Add folder: add it, wait for the scan, and import again. The button names the result, for example Import 48 playlists.
Beatgrids are not imported: Solco grids every track itself. Comments and play counts stay behind too.
Your preparation always wins
A rating, colour or hot cue you already have in Solco stays as it is. Imported playlists go in one folder per app: rekordbox, Traktor or Apple Music. Importing again updates only the playlists you haven't changed since, never brings back one you deleted, and never removes anything. To start an app's import over, delete its whole folder.
From a USB drive
To bring tracks, playlists and cues from a USB drive prepared by rekordbox or Solco, plug it in, open the Export page and click Import from USB. To keep only the sets you played, choose them under Play histories and click Import histories only.