In 12.4 you cannot download the documentation set in PDF, like previous versions of DCRUM. However, you can export it!
I think this is great since you do not have to wait for the PDF's to be updated. You can export it whenever you wish. Now, it may take a while to generate the PDF, but I prefer it over the old method.
To export the 12.4 docs - go to the documentation home for 12.4. In the upper right-hand side there is a Gear Icon with the tools label. Click on the pull-down and select "export to PDF". I like using the "Book Template (with Child pages)" option.
This also works on individual sections of the documentation. Open the main subject for the section you want and perform the same action.