How to accept a shared album invite on iPhone
New shared album invitations show up in Notification Center. If you can't find your invitation there, you can check the Photos app.
Find your shared album invitation in Notification Center
Go to Settings > Photos, and make sure that Shared Albums is turned on. If this setting was turned off, ask your friend or family member to resend the shared album invitation.
Open Notification Center: From the Lock Screen, swipe up from the middle of the screen. Or from any other screen, swipe down from the center of the top of your screen.
Tap the shared album invitation, then tap Accept or Decline on the album in the Photos app.
Find your shared album invitation in the Photos app
Go to Settings > Photos, and make sure that Shared Albums is turned on. If this setting was turned off, ask your friend or family member to resend the shared album invitation.
Open the Photos app and tap the For You tab.
Scroll down to Shared Album Activity, then tap Accept or Decline.
If you still can't find your shared album invitation
Check that you meet the minimum system requirements for Shared Albums. You might need to update your iPhone.
Check your email: Ask the person who invited you which email address that they used to send the invite. Then search your email for their name or the name of the shared album.
If you accidentally declined the invitation or now want to accept it, ask your friend or family member to resend the shared album invitation.