In order to access Forsaken (or the Forsaken Annual Pass) content, then players must purchase that content on the platform they wish to have access on. Since D2 isn’t currently on Steam, it is only purchased through blizzard (that will obviously change come September when D2 moves from blizzard to steam). So, you can either purchase the complete collection now on blizzard (and it will transfer to steam once the transition occurs ), or you can wait to buy it in September on steam. Furthermore, no version of Shadowkeep comes with any Forsaken/Annual Pass content, as these aren’t required to play/buy Shadowkeep. You only need to buy Forsaken/Annual pass if you want to play/access the content from their licenses.