If you purchased the Shadowrun 4 Core Rulebook PDF from Catalyst or Drive Thru, you should have received an updated Download Link through the purchase site to a newer version of the book when Errata was released.
The same applies to Shadowrun 4 Anniversary - although there has not been any Errata actually released for this yet, there was at least one change to the PDF made prior to the print release, specifically addressing the Direct Combat drain and bow damage.
If you never received an updated PDF link, contact the customer service of your purchase site.
I do not believe (although I could be wrong) that you will be given an updated download from the original core rules to the Anniversary printing - to obtain the Anniversary, you will have to repurchase or rely on the update document.
