Does Meditation target a unit to draw on Dreaming Tree?

No, Meditation does not target a unit, and therefore it does not trigger The Dreaming Tree.

Reasoning

1. Meditation's Cost vs. Effect: According to the card text, exhausting a friendly unit is an additional cost to play Meditation, not an effect of the spell. Rule 352.10.c states that objects included as part of a cost do not target.
2. The Dreaming Tree's Trigger: The Dreaming Tree triggers only when a player "chooses a friendly unit... with a spell." Because the unit exhausted for Meditation is part of the cost and not a target of the spell's effect, the condition for The Dreaming Tree is not met.
3. FAQ Confirmation: Multiple RiftJudge FAQs (524, 2138, 1123, 206, 3276) explicitly confirm this interaction:
   • "Meditation does not trigger DreamingTree's battlefield ability."
   • "Exhausting a unit as an additional cost for Meditation does not trigger DreamingTree's ability to choose that unit."
   • "Choosing a unit as part of paying an additional cost is not the same as targeting that unit."

Summary of Meditation Resolution

When you play Meditation:

• You choose whether or not to pay the additional cost of exhausting a friendly unit.
• The spell does not target a unit, so The Dreaming Tree does not trigger.

Note: I could not fully verify the specific card draw amounts mentioned in the draft against the retrieved rules.