To update how you receive notifications about what's going on with your group album:
Go to the screen where it says "Your Group Albums" (where it lists all of your group albums) and select the profile settings icon in the upper left-hand of the screen. Select "Notifications Settings". Here you can select or deselect the email icon and/or the phone icon to the right of any of the options listed (i.e. Posts, Members Added, Comments or Likes) to either get notified or not get notified about the respective activity. When you are done be sure to select "Save" in the upper right-hand of the screen to apply these changes to all of your spaces.
(iPhone/iPad only) If you want to turn off notifications for just one of your spaces:
Go to that group album and select "Notifications" (the bell icon) in the toolbar at the bottom of the screen. Here you can select the speaker icon in the top right-hand corner of the screen. When the speaker icon has an "x" to the right of it, you have successfully muted notifications for this particular group album. You can also go to that group album's "Settings" (gear wheel icon at the far right of the bottom toolbar) and toggle "Receive Alerts" so that it is no longer on.
You can update your email subscription settings here (these are the emails you get from the Cluster Labs, Inc. team, not to do with activity/interaction happening within the app):