Yep, you have the right thing.
Azithromycin 250mg (generic
Zithromax)
It is made by Greenstone which is a subsidiary of Pfizer who holds the patent on the Z-pak/Zithromax.
There has been some recent legal battles over this particular drug. Pfizer petitioned to have the Sandoz generic and Teva generic recalled claiming copyright infringement. The Sandoz and Teva versions are both still on the market and I guess Pfizer wanted to get in on some of the generic money. So in turn it produced it's own generic version through a subsidiary, Greenstone.
I write this because I find it weird/interesting that Pfizer basically produces both the "brand name" and a generic at the same time.