Not 100% how they track it but i am quite knowledgeable in anonymity.
I would say these things can get you banned
VPN: A VPN is a virtual private network and it just masks your current ip address this VPN either free or paid is probably being shared with other people as they have a private server and it would be used by 100 or even 1000s of people NORD VPN. You can either use a cafe or a free internet or one of your mates it is easily detectable it you are on a VPN and they can ban you probably in their terms and conditions.
Make sure that when creating a new account you have no data/info under your current acccount eg. email/phone number.
Make sure you are using a completely different computer yest computer as they can track what your mac address is and this can be linked to your account. You would have to clear your cache and computer cookies this can all say be linked to your account. you can use an RDP remote desktop protocol which is a server were there is an operating system running on it. This can mask all your computer information as it is not your computer you are using a server computer.
They probably would look into your account as $1000 matched bonus bet is very high and if you turn it over straight away they will just ban you. You would have to slowly turn it over and place lots of mug bets and try lose those mug bet.
This is quite complex and if you do this you will not get caught but you would need to plan ahead as if you do one mistake they will promo banned you and all that money will be deducted from your account