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No worries, I have the same since I registered actually. In fact, I never even got the user ID until now for some reason. I checked several times but never saw it, always the same message as your's. Not sure if we actually need the ID since the email (or phone number) identifies your account as well if you ever need some help from the support.
I noticed the same thing today when I re-registered my account, for example, I couldn't register an account using an email address, only a Telegram registration was possible.
I think I also noticed similar thing too, because my first registration was my email address so when I was trying to log in to my profile it was very hard for me to access it. And I was directed to re-registered my account again, I now have to use Telegram to registered the second time, and after that till now I haven't had any problem on my account, everything is just working perfectly. However, I think using via Telegram to register is always the best.
Whale casino started as a casino running on telegram as a mini app, and basically for me, I have not tried logging in on the casino from any other place aside from telegram, and I have never had any issues at all since I joined and have played on the casino.
But however, with the casino growing in popularity and more user coming in, it's advisable that they make other means of sign up and login available and working properly, because it's not everyone that will find sign up and login through telegram convinient at all time, for example, what happens if and when a user's telegram account have issues, like a ban or something else makes them loose access to telegram or their account, and they wish to access their account on the casino from a different device or source, what then happens?
This is why I think they need to really work on making other means of sign up and log in working perfectly well just as sign up and login through telegram is working at the moment.