psql: FATAL: password authentication failed for user "GuardDog_02"
When issuing CREATE USER GuardDog_02... the exact user name created is 
guardgog_02 because of SQL case folding. You may check that with \du in psql.

But according to that error message:


  psql: FATAL:  password authentication failed for user "GuardDog_02"


the username you're trying to log in with is GuardDog_02 (G,D in capital letters), which does not exist with this capitalization 

To create that exact name, the identifier must be enclosed in double quotes, as in:

CREATE USER "GuardDog_02" WITH PASSWORD 'apple100' CREATEDB CREATEUSER;


Or, alternatively, if you don't want to recreate the user, log in with psql -U guarddog_02.