Yes, but no.

The soundtrack is still available, however, the minion codes for the earlier OST albums are not, as they have long since expired like the one that was included with Before the Fall, and will no longer work even if you can find a copy with an unused code sadly (so those minions are now unattainable).

As I recall there is usually only a two year window from when the album was first released to the codes becoming invalid (so for Before the Fall that would mean it would have expired around 2017).

So yes you can still buy the soundtrack, but the minion code that was offered is no longer available sadly.