When i press the first key on the keyboard it plays c5 note from the kick.
And when i press the next key on the keyboard it plays c5 from the clap and so on.
How else would it work? If the first key triggers the first sample, the next key triggers the next sample. In FL, c5 is middle c which is the key where samples are loaded in their original pitch. How would you like it to work?
Sounds a little weird to me. I'd recommend reading the FL studio manual. Even if you only want answers to this question right now, it'll save you a lot of questioning. Reading the manual should be mandatory before even being able to open any software imo.
I doubt there's anything wrong with the keyboard. You probably just didn't set it up correctly. Which you might be able to do if you actually read your manuals.