Hi @Sam_Kim1, welcome to the forums.
The Zwift mountain bike was “given” to everyone late last year I think when they released the other new mountain bike models and the gravel bikes. It should be in your garage already and you didn’t need to win it, please note that you must stop moving (0 watts) in order to change bikes when riding. Also, make sure you aren’t looking in the drop shop, you won’t find it there since it is already in your garage.