Creating a database with authentication enabled on mongodb

I can create a database using a specific role for my "user1". I have tested and a user "test1" can not create a database in the mode authorization enabled. How works the creation of the database? I created a user "user1" and it can access this database "db1" only. Can I have the same user "user1" with privileges to create a new database as exists in SQL Server? I might be (completeley) wrong, but I would like an explanation concrete about this case. Thank you for any help and instruction. :)