Migrate Sync from 2 to 3b?

Is there any way to migrate my sync settings from DTPO 2.x to DTP 3b?

Yes, you can move the folder ~/Library/Application Support/DEVONthink Pro 2/Cloudy to ~/Library/Application Support/DEVONthink 3. But don’t copy this folder and only move it if you’re really going to switch now.