There is no requirement for you to print anything out as all tickets can be opened and scanned digitally.
You are more than welcome to print things out if you want to have a copy of anything however if any details change, this update will be sent to your app and would not be reflected in any printouts you already have so can become outdated quickly. (You will always be notified of any changes via an app message).
If you phone battery dies, we still have our own backups to ensure you can still do what you need to do during your holiday by giving us your name (with ID) to enter events and to collect items.