Hi and welcome to Arturia forums.
In generel you need to set up any keyboard controller in your DAW to make it work.
It shall be set up as a keyboard and as control surface for your DAW.
I don't use FL Studio or a Arturia keyboard. But try to do like you can see in the image posted by Matt Arturia in reply #3 in this thread
https://forum.arturia.com/index.php?topic=91343.0 .
Log in to see it.
Also you can find info to set up Keylab Essential as a control surface in your DAW here:
https://www.arturia.com/faq/keylabessential/keylab-essential-tips-tricksAnd Image Line should have a guide for their DAW to follow.
If you are interested there are some videos here about your controller
https://www.arturia.com/keylab-essential-61/mediaI don't think they are about how you can set up your controller in your DAW though.
FYI: you have posted in a forum for a old Keylab. Keylab Essential have it's own forum.