If an Aura is put onto the battlefield without being cast, the Aura’s controller-to-be chooses what it will enchant as it enters the battlefield. An Aura put onto the battlefield this way doesn’t target anything (so it could be attached to an opponent’s permanent with hexproof, for example), but the Aura’s enchant ability restricts what it can be attached to. If the Aura can’t legally be attached to anything, it remains in its current zone.

If there are fewer than X permanent cards in your library, you exile your entire library and put the permanent cards in it onto the battlefield.

Any cards that you exile but don’t put on the battlefield for any reason (for example, because the card is an instant card or an Aura that can’t enchant anything) remain in exile.

An Aura being put onto the battlefield this way can’t enchant anything else that is being put onto the battlefield at the same time.

Auspicious Starrix’s effect doesn’t count as playing lands. It can put land cards onto the battlefield even if it’s not your turn or if you’ve already played your land for the turn.