How to link my Italia Pass membership to the trainitalia app?

So, I am trying to make reservations/book train tickets using the app trainitalia.

And

Also want to see on the app trainitalia the existing ticket reservation that I purchased at the same time I purchased the Italia pass.

How do I link my Italia Pass membership to the App trainitalia to view my existing ticket reservation and any new ticket reservation as well?

Thanks

Jen

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