Engine only copies files when you export to a “performance” volume. That is, the SD Card, USB Thumb Drive or Internal SSD volumes that you use to play music (perform your DJ set).
When working with source music, it uses the database it creates and maintains to help you manage that music in its source location only. The only time it seems to change things is:
On some formats, it will act as a tag editor
When you remove from collection, it will delete the file, bypassing the recycle bin
There’s no need to create a folder on the destination drive, or copy MP3s on to it.
Step one is to open EngineDJ, then import the music from your source drive (i.e. the drive in your computer) to EngineDJ to create a database, playlists etc.
Once the database is created, you can then sync (using Sync Manager) the data to the destination drive.