Unfortunately, that's a common thing for almost all new and even old reputable bookies. Big win = Locking account and refusing winning payout.
If you want to bet completely anonimous, privately , without someone asking for KYC, from every repeat every country in the world, without being limited for whatever reason, without running the risk of having your account blocked/seized/closed...then your only alternative is blockchain based betting.
I use WGR (wagerr.com) to do so and their odds are amongst the best and their betting offer is growing steadily. Am happy with them.