So, in the screenshot of the log there’s this line:
Access denied for user 'root'@'localhost' (using password: NO)
This seems to indicate that in the setup wizard, when setting up the connection, you entered the user name for the database user, but left the password blank. Unless your MySQL instance is configured to accept passwordless connections for the root user (and this actually requires a bit of manual configuration to make happen), you need to supply the password for the root user in the start-up wizard. From the screen you’re currently on, you can just click the green arrow and go through the wizard process again.
From the instructions you linked to:
Here, you should see a box asking for a password. This is the password for your mySQL. This is the same password that you used to start the SQL server earlier.