No there isn't! The cloud feature is a part of MIXO:GOLD which is open to everyone during the beta.

MIXO:BRIDGE is a part of the free version of the app.

All you need to do is go to Settings > Import > Serato and browse for the crate you would like to transfer and then once this has completed go to Settings > Export > Rekordbox and save where you like. Make sure to go to Preferences within Rekordbox and select the path for the new rekordbox.xml file that MIXO created.

If you run into any issues - let me know!