The eBook uploaded to the eReader platform is often the source file that the publisher uses to print the physical book. This means any media, publisher product/access codes, CDs, lab manuals, etc that might have come bundled with the physical book are unable to be included with the digital version for formatting and copyright reasons.
You can find some supplemental material for free on the publisher's website. Be sure to check and see if they have that content available.
And don't hesitate to submit a request if we can further clarify or help with anything else!