Yes you can wear jeans, but there isn't really a dress code. I wear jeans with some dark colored retro style new balances and a button up shirt and I'm fine. If you want to have fun, DONT WEAR DRESS SHOES! Jumping around and dancing in those will only last a few minutes, trust me.

I guess since you are paying for the ticket before hand with another company then they cant really enforce the dress code all that much because if they deny you, it could start conflict with the club and groovetickets. Just a guess...