Hello,
The complete set of instruction on how to use SAS OnDemand for Academics and how to download the data for SAS OnDemand for Academics can be found when you click on the link for the practice exam. You will need to have a SAS account. The link to free practice exam can be found here: https://www.sas.com/en_us/certification/credentials/foundation-tools/base-programming-specialist.htm...
You will sign in to your SAS account and access the exam for SAS Certification Practice Exam: SAS 9.4 Base Programming Performance-Based Exam. Once you are at the exam page, you will see a header: Access SAS and Set Up Files for the Practice Exam (Required). From there you will see instructions for Using SAS OnDemand for Academics and for how to download the data.
I would also recommend downloading the Exam Content Guide and recommend that you use it to help inform and guide your study efforts before attempting the practice exam. The Exam Content Guide can also be found on the same page URL provided above.
I hope this helps. Good luck to you in your studies.