OSStatus Error 54

i am coming from Rekordbox, but tbh DJpro is a messy experience so far.
I imported my music as mp3 files, coming from my Rekordbox library, after finding the playlist options (also not as easy compared to Rekordbox) I got it right.

So the files are directly on my Macbook now, and I could put them to my collection.

If I want to load a song (simple in deck one), the whole system crashes and the OSStatus Error 54 shows up. Then Djpro quits itself and crashes.

There is no way to use this program right now.

Using MacCatalina