That might likely be a bug or some sort of network issues of possibly, you can clear your cache and try logging into your account again. Everything is alright from my end here. If it persists you can change browser as well and see what happens.
Not network issue though
(there should be a different error related to it), used different browsers both mobile and desktop. Note that this happens after i register, confirmed my email and tried to login but unfortunately, this happens. So i can't still open my account yet.
Is your country amongst the restricted countries? Or possibly it might be a technical issue from the casino. You will just have to wait and be patient with the team to resolve the issue and get back to you.