Does Ravenbloom Student ability require the spell to resolve?

Yes, Ravenbloom Student's ability requires the spell to resolve.

In Riftbound, a card is not considered "played" until it successfully resolves. Since Ravenbloom Student's ability triggers "When you play a spell," if a spell is countered or otherwise fails to resolve, it is not considered to have been played, and the ability will not trigger.

According to Rule 412.1.b and consistent with multiple RiftJudge FAQs:

• Sequence: You play a spell (it enters the chain) → The spell resolves → Ravenbloom Student's trigger activates and is placed on the chain → The trigger resolves.

If the spell is countered, it never reaches the resolution stage, and therefore the condition "When you play a spell" is never met.