Required Certificates for iOS-App Update


I have an App that is currently in the AppStore and which should be updated with the latest version now. I tried to work through this and this documentations, but honestly I did not understand which certificates I really need.

I did not publish the app in the first place - do I need exactly the same certificate that was used when deploying the app for the first time? Can someone provide me a list of what certificates I really need to have for the update?

The certificates seem not to be mentioned in the command to create the .ipa, so I assume that they should just be in the root directory of my project?