Devil's in the detail
So key here is "customer's enrolled mobile device". According to the blurb;
"With this option enabled, your video content is encrypted with a unique key generated by your Ring device, and this key is only shared with the mobile devices you select. Only you have the key to decrypt the videos.
Please Note: Enabling End-to-End Encryption will disable some of the features you get with Ring devices. For example, you can't watch Live View from enrolled Ring devices on an Alexa device. Also, any Shared Users you've added will lose access to Ring devices you enrol."
So you can enrol a few devices under your own account by the sounds of things, but any "shared" users (not logged in under your account) within your household can no longer access them. Plus you lose the love view function on any Alexa devices. hmmm...