Based on your information, I would consider this piece of information "complementing" the main content. In that case, a normal section would do, and you could use the complimentary role.
As a screen reader user, I would really prefer this information not to be repeated at every step. This is a large chunk of information, and when I click on "Next", it would be quite unexpected to have my screen reader begin reading it. If you want to alert the user to the fact that the steps have changed, you can do one of the following:
- Have an invisible HTML element with the aria-live attribute set to polite, and use it to report that a content has changed (I.E. by adding a text such as "Summary updated").
- By explicitly mentioning in the text that the summary will update as you complete each step.