The ONLY things I found that are legal to study from are:
- Taking the course by Oracle (which is very expensive) --> https://education.oracle.com/products/courP_4601
- Study guide by Oracle (which is free) --> https://www.oracle.com/partners/en/most-popular-resources/oracle-adf12c-2205879.pdf
This then prepares you for the 1Z0-419 exam https://education.oracle.com/oracle-application-development-framework-12c-essentials/pexam_1Z0-419
Anything else you Google for will be ILLEGAL brain dumps which you should NOT study from.