This bundle is invalid. The IPA format requires a top-level directory named Payload, containing only a .app bundle and optional plugins in a Plugins directory. (ID: df59dbe4-17e5-4bc6-9c69-8645672320(4))
Since Unity created this project for you, you'll need to inquire with their support on how to resolve it. There is something in the project they created for you that is the source of this, as a standard project created through Xcode File > New Project will not have this issue.
— Ed Ford, DTS Engineer