Have you checked your Feats for crafting recipes? The Twitch Drops reward items aren’t the items themselves, they’re the recipes to craft the items. The placeables would be under Decorations → Furniture Maker and the armor set is under Armor → Exile Epics.
Oh, maybe I misunderstood the question. You had about 24 hours after each day was over to physically claim the item from your drops inventory after you earned it. If you didn’t claim the item by then, the reward will disappear from your Twitch account.
Twitch itself would notify you when you earn a Drop; the alert would show up in the chat area or as a popup if you’re on the mobile app. Remember that only streams with the “Drops Enabled” tag would count towards your progress.
In any case, we may do more Twitch Drops campaigns in the future and make these items available again for a future Drops event. Keep an eye out!