Hello 105826,
I also do not know the technical characteristics of Oracle 12C, but searching for the error message, I could see that you created your database with the "Oracle Database Vault" option.
Vault would correspond to an additional security layer that is added to the database. You can get more information about it in this link in Portuguese.
http://www.oracle.com/br/products/datab ... index.html
Now, I understand that your goal is to only study the Oracle 12c bottom. In this case, the functionality of the Oracle Database Vault does not need to be activated for the breeding of the bank. It is a product that does not usually be installed if the goal is the study of the bank.
In this case, you would have three options:
a) Remove the created base (check how to do this) and install the same again, but without the option vault;
b) Keep the base created, but remove the vault option (see in this manual:
http://docs.oracle.com/cd/E16655_01/ser ... e17608.pdf Annex C);
c) Study the Vault and seek to set the same (use the same manual of Option C, but remember that you will be moving away from your goal of studying the database);
Hugs and good luck,
Sergio Coutinho