Opentuition F3 PDF textbook file – “a number is out of range” error

Hi,
I downloaded the F3 textbook from this website.Any time I try to save it with my editing I receive an error message from Adobe: “a number is out of range”.
I checked on internet and apparently this is a difficulty that just the issuer should solve.
Is anyone aware of it? Is a new version on its way?

In the meantime, thank you for your work.

Kind Regards,

Mirco