If you got a used book you'd have to purchase the connect plus access code online separately because the course outline says that the course will be using the online component and the older version of the book doesn't even have an access code.
I'm pretty sure that for the access code in anatomy you have the choice between a "connect" code and a "connect plus" code, which is more expensive. The only thing extra you get with the connect plus code is an online version of the textbook. In the example on the website, the "connect" code was only about 25-30$, but that was for a different course, so the price could be slightly different.
You should probably wait until the first class before getting everything sorted out, because they'll most likely cover most of this... hopefully!