To complete this challenge you need to win a number of times with a multiplier. The challenge description states how many wins and what the multiplier of each win has to be e.g. 5 win with a multiplier of 100x or above. A win multiplier is how many times larger your win is compared to your bet.
Example: if you stake €1.00 you would have to win €100.00 five times on any slot.
Please note that minimum stake for challenges is €0.40 (or more)