I created sportsbet.io account, entered my username, email and password and right away I was logged into the system.
I closed the page and walk away for some time but when I tried to log in during another visit was greeted by 'sign in' popup - where I imagine I have to enter my email and password, right?
But when I click on green 'sign in' box nothing is happening - oh and there is: google authentication check box too!
But I don't have google Authenticator, so how I can log in from now on?
You dont need to tick the google authenticator tick box if you dont use it. Simply put your id and password and just straight with login. Sometimes the server seems to be taking longer time to respond however it should be fine unless there is another warning / pop up saying id or password is wrong on your end
Now site is working fine and I can log in with no problem; and as you said google autheticator is not needed.