I've seen this mentioned on here a few times - Albion+ members being added to season ticket waiting list.
I'm sure you are correct that you need to opt in - it's not automatic. I signed my two lads up last summer and can remember having to tick a box (or something like that) to join the list...
If I recall ... on the occasion I did it earlier this season ... I received an email to forward onto my son so that he could add the e-ticket to the wallet on his phone ... as opposed to a paper ticket.