Haven’t seen other reports of this yet, so let’s narrow it down.
Open build.tadabase.io in a Chrome incognito window and try signing in. If that works, it’s a cookie or extension issue in your normal profile. Clear the cookies for tadabase.io and try again.
If incognito fails too, press F12, open the Console tab, try the sign-in, and paste whatever shows up in red here (or email it to greg@tadabase.io).
Which Chrome version are you on? That’ll tell us quickly whether it’s something on our side.