You could use the relevant Admin Guides from the R81.20 home page:
https://support.checkpoint.com/results/sk/sk173903
You are looking at documents that together contain thousands of pages, and you have no lab steps/instructions.
If you went that route then you could gain significant knowledge on Check Point Quantum products.
You would go way beyond the required reading for the exam, unless you read the course data sheets to try to narrow your reading to specific topics within the Admin Guides.
It may be worth looking into purchasing the books only. They are actually a product (E-Kit) in the Product Catalog.
It's not the default way and may not be easy, or even possible, but if you got the books you would have focused study material that are the source of the majority of the exam questions.
You can read more on the books, the layout and book hosting platform (Kortext).
https://community.checkpoint.com/t5/Training-and-Certification/Clarification-on-the-E-Kits/m-p/22893...
Honestly the best option is to try to get on the courses.
You will get the book (with lifetime access) as part of the course and lab access.
Maybe you can contact the ATC/s and ask for a discount. Maybe they can add you to a wait list or offer a discount based on your situation and also based on you wanting to attend both CCSA and CCSE.
For reference, the CCSA and CCSE books are 906 and 784 pages long, respectively.
https://training-certifications.checkpoint.com/#/courses/Security%20Administration%20R81.20%20(CCSA)
https://training-certifications.checkpoint.com/#/courses/Security%20Expert%20R81.20%20(CCSE)