In the authenticate user behavior, on the Database tab, you should selecting the Username and password columns and binding the, to the username and password form elements.
On the session tab, you should be saving the ID column as a session, you can save other columns if you wish, but the ID column is the only one that is really needed.
in the access rule, it should be configured as:
Allow if
Variable: click the lightning bolt and select the Used ID Session
<> (Not Equals
Comparison: leave this blank.