I play Fortnite and my keyboard is pretty broken and now I'm looking for a cheap (under 40 euro) gaming keyboard with LEDs
Wonderful! Look for keyboards from "KLIM":-)
https://m.ebay-kleinanzeigen.de/s-anzeigen/deutschland/gaming-tastatur/c0-l0
I would just make sure it's a mechanical keyboard.
There are different versions, that's a matter of taste.
For 40 euro you will find a good beginner version