Log into iCloud Photo Sharing on Apple TV for access to shared albums on the big screen.
iCloud Photo Library is Apple’s photo storage service, which lets you store all of your hundreds of thousands of pictures in iCloud. Doing so makes it possible for you to grab the photos you want onto your device without having to store them locally. You can connect all of your photo uploads by setting up iCloud Photo Library on your iPhone or iPad, and Mac or PC.
When you turn on My Photo Stream and iCloud Photo Sharing on your iPhone, iPad, and Mac or PC, you can view your shared iCloud Photo Library on the fourth-generation Apple TV, as well as pictures you’ve added to My Photo Stream over the past month. Once you are set up on iPhone, iPad and Mac or PC, follow the steps here to access your photos on Apple TV
How to log into iCloud Photos
Turn on Apple TV.Open the Settings app.
Select Sign in.
Enter your Apple ID.Select Continue.Enter the Password associated with your Apple ID.
Select Sign In.
Select iCloud Photo Sharing to toggle it on.
Select My Photo Stream to toggle it on.
When you open the Photos app on Apple TV, you will see your shared albums, recent activity, and your Photo Stream feed. You can view pictures as a slideshow, or set them as the screensaver.