"To create a schema, the invoking user must have the CREATE privilege for the current database. (Of course, superusers bypass this check.)" - maybe you can show how to check if the user has the CREATE privilege? Or is this omitted on purpose so readers will take their own initiative to find that out themselves :-)
In the interest of brevity it is assumed the reader is familiar with the definitional chapter regarding privileges and can use the knowledge gained there to perform such database inspection.
I thought it has to do with specific CREATE privilege.
The user in question has the Create role only when I did a \du+.
I thought that would not allow him to do a CREATE SCHEMA but it did. So I am guessing so long as the user has the CREATE, it is allowed to do the CREATE SCHEMA.