Access denied in created rule - Firebase

Guys, I saw this post here on the forum: Securing Firebase - Kodular Docs
By the way, excellent. I’m having problems with my rules in Firebase. The authentication system is via email and password. My Database had this structure:

To do this I left the rule in default mode.


When I tried to change the execution mode in an attempt to register, I got this error for this rule:


I did this for other real-time rules but the message changed to access denied:

Can you help me and what am I doing wrong?