It's invite only in that you need to have previously owned a New/CPO BMW. So I do normally I start my call with something like "I received an invite"
Then they take my VIN/info and say they will check if I qualify and reach out back to me. In my experience they didn't promptly respond back so I call back after ~3 business days and then they proceed with signing you up.
2012 - Invite came on a postcard
2016 - Invite came in email and a physical box with a USB in the shape of a key fob
2018 - Invite also came in email and a physical box with a USB in the shape of a key fob
2022 - Invite was email only this time.
The email is really easy to miss. Gmail puts it in the 'promotional' folder and at a quick glance it just looks like junk mail from BMW.
This is the 2022 version.