I went to a group Bithumb Global English, it has thousands of members, I msg the admin, immediately the telegram group goes private which give me a scare.
Their official Telegram group is Public.
Maybe you landed on a wrong group but I can't see any group with thousands of members that are identical to their official group's name.
Here:
t.me/bithumbglobal_ENAnyone here using Bithumb and which is the correct site to register?
Refer to the post above. All URL's are given correctly.