I’ve just purchased this (Pipe Organ) too and am having the same issue. It isn’t showing in Product Manager.
I received an email but there was no serial number. I was (and still am) logged in at the time of purchase.
I purchased Mellotoon a week or so ago and that worked fine.
Bump to Grandaddy and Joe here. I use a TMC-6 with my TD12 and TD20 and it works very nicely with SD2. The triggering is just as good as my 12 and 20. 🙂
