That's a good start! Well done!
The key elements:
- Who your MC is: check.
- What’s at stake: um... not there...
- Essence of plot: check.
- Genre: not stated explicitly, but the age range indicates YA. so, check!
- Bonus: What makes your story unique: not really, no...
- Bonus: Conveying the voice: nope...
So, stakes, uniqueness, and voice to really bring it home... Here's a suggestion:
Sixteen-year-old Abby Wintelan's biggest concern was passing her driver’s test—until she’s drafted into a decimated magical army to stop the big bad from doing the awful thing [like maybe... to stop the dread unicorn from devouring humanity's ability to feel compassion].
As written, your story is only about her being drafted. Yeah, that probably sucks, but we don't know WHY it sucks. Honestly, if a group approached me and said, "You're coming with us Kuriel, we need your magic." I'd say, "Okay... I get to learn magic and do something awesome!" So tell us what the awful thing is and ensure we can easily understand why it's awful.
My other changes, most readers in your target audience probably understand the challenges of being a sixteen-year-old; establish her most pressing concern and move on.
It's highly unlikely that an 'elite' army of any sort is going to press-gang raw, untrained recruits. So I changed 'elite' to 'decimated' to show that the army's fallen on hard times and is growing desperate. Keep it if it suits your story and tone.
More about tone: use words that Abby uses in the story, or paint her personality as part of the opening. "A sixteen-year-old goth girl's greatest impending failure is her driver's test - until she's drafted by a magical army to stop the angel of joy from using happiness to destroy freewill."
Hope that helps!