You will need to learn about data structures and how to traverse them. There are already replies with links to perldsc and maybe other tutorials.

If you refuse to show us the data structure, how do you expect us to give you code that will traverse an unknown data structure?

If you get errors while traversing your data structure, that usually means that your data structure is not what you think it is.

Please also note that XML::Simple is a bad choice for ingesting data which may or may not have multiple elements somewhere in its structure. See also the ForceArray parameter in its documentation. But again, this boils down to you not showing the relevant parts of your data structure and your incoming data.

Until you understand your data structure (by using Data::Dumper), and/or understand what parts of your data structure are arrays and what parts of your data structure are hashes, there is little we can do to help you.