I have a KeyLab Mk II 61 and had issues using Reaper as my DAW.
Questions that tech support will ask you:
1. Have you used the MIDI Control Center app (MCC) to manage your keyboard?
2. Have you updated your firmware via the MCC?
3. Have you selected the correct DAW in the MCC?
If you have done all of the above, you may need to reach out to tech support and specify the issue as the keyboard not correctly programming the FL DAW mapping. Arturia said Reaper connectivity is an issue they are going to address via a future firmware update, but they had to provide a manual configuration setting for me to use Reaper. It's possible you have the same issue with FL as I did with Reaper.