If you don’t have access to the internet, you can still watch or listen to things you’ve already downloaded. 
Not sure how downloads work? Check out: How do I use Downloads?

When you’re not connected to the internet, you'll be given the option to tap Go To Downloads or Reconnect. Just tap Go To Downloads to access all the Movies, TV Shows or Music you’ve downloaded. You can also access your Membership ID card from here.

Remember: you’ll need an internet connection to stream, or to download something new.

If you're going abroad, make sure you take a look at Can I use DisneyLife abroad? before you go.