I have not used the install package you have used. However you can try the following. First check if the root user exists.
Execute the following code:
SELECT User
, Host
, Password
FROM mysql.user
WHERE User='root'
This will return a list of the users with the root userid. You SHOULD have at least one root user listed there. If I am correct you will see root listed but the password column would be NULL or BLANK.
You would now need to set the password for the root users. There are a couple of ways you can do this the first way is to use the SET_PASSWORD method.
Example of SET_PASSWORD method:
SET PASSWORD FOR 'root'@'localhost' = PASSWORD('newpwd');
The other way that is commonly used is the UPDATE Method.
Example of the UPDATE method:
UPDATE mysql.user SET Password = PASSWORD('newpwd')
WHERE User = 'root';
FLUSH PRIVILEGES;
This method will update the mysql.user table directly and you would need to run the FLUSH PRIVILEGES to make sure the system security is reset.
If you dont have a root user you will need to create it.
This link is worth reading https://dev.mysql.com/doc/refman/5.5/en/default-privileges.html as it shows you all about default settings etc.
If you need to create a new user please check the following link http://dev.mysql.com/doc/refman/5.1/en/create-user.html.