When using the Firebase Sign In blocks, you would typically not need the user’s email address. Everything in Firebase would be stored based on the user id. The only reason to store the email address is if you plan to send email messages to it.
I recommend watching this very good tutorial: Authenticating users with Firebase (with video tutorial)
And @Goldking is correct… you can’t compare values in a row id text field because that would only return “true” or “false” which are not row ids. You need to give it a row id value (a long string of numbers and characters) or an integer.