Most good stories start with a fundamental list of ingredients: the initial situation, conflict, complication, climax, suspense, denouement, and conclusion. Great writers sometimes shake up the recipe and add some spice.
Since this is an autobiography, Survival in Auschwitz doesn't really follow any kind of standard plot progression or framework. Levi did not write this memoir with a particular structure in mind. Instead, it's a first-hand account of Levi being captured and taken to Auschwitz. While he's there, he sees how the men and women progressively lose their humanity because of their brutal treatment. Even after the SS and other Germans leave the camp because of the impending arrival of the Russian forces, the remaining prisoners continue to live with sickness and abject filth and sink deeper into fear and despair. In the end, Primo and a few other prisoners are able to retain their humanity because they band together and support each other; they're not just out for their own survival.