I'm assuming I don't have "My photo stream" because I'm not familiar with it. Is it a stand alone app or an extension?.i.e., where would it be found if I have it? As far as I know, all of my family members use iCloud. The previous iPhotos to Photos transition was a big hassle, but this doesn't sound like that.
MacBook Pro 15″, macOS 10.14
As explained in the support document you posted from, My Photo Stream can be found in the Photos App. It is an album there if you have turned on the option in Photos Menu ➜ Settings ➜ iCloud on your Mac.
It is not an app nor an extension. It is a service you access within the Photos App.
click here ➜ My Photo Stream - Apple Support
You would only receive an email about it, if at least one of you'r devices has the option turned on.
As explained in the support document you posted from, My Photo Stream can be found in the Photos App. It is an album there if you have turned on the option in Photos Menu ➜ Settings ➜ iCloud on your Mac.
It is not an app nor an extension. It is a service you access within the Photos App.
click here ➜ My Photo Stream - Apple Support
You would only receive an email about it, if at least one of you'r devices has the option turned on.
You may have used My Photo Stream with iPhoto or Aperture or an Apple TV. Apple's older photo applications have been deprecated when Photos come out. If you only ever used My PHoto Steam with iPhoto or Aperture, you don ot have to worry now about the photo stream.
Question about "My photo stream" notice from Apple
