The API Section only tells you about GooglePAD library functions and potential error messages they can trigger, it doesn’t include anything about what you need to implement.
There is important information missing in the UE documents that are critical to make fast-follow and on-demand asset packs to work and requires a bunch of C++ to get working correctly.
So there is actually a hard limit for each of the GooglePAD features you can use, the install-time version which @Vrai17 mentions is 1GB and you can’t have multiple install-time asset packs.
If you’re looking for more information other than the Unreal Engine documents, feel free to check the docs attached to my plugins forum post, even without owning the plugin there is a lot of information that can be useful, check out the Q&A section in the PDF for asset pack limitations or tips and tricks.
Hope it helps!