You don't. It is public domain. You pay that if you want to get it from them. This is the same as I can get a free pdf of "Linear algebra done right" from Sheldon Axler's website but if I want to get it from Springer I pay $50 or whatever it is.
In many cases, it's value-added, because the bundler may also do some curation and interpretation.
Not sure that's what's happening, here, though...