Yes, I'm familiar with the brand and use that product, it's great. Check where the seller is sending it from when it's significantly cheaper, it's a South Korean brand and when it's sent from there it tends to be much cheaper but shipping is usually between 2-3 weeks. The product itself, and the brand, is absolutely fine for teenage skin, it's very gentle (most South Korean brands tend to be). It's a bit of a myth anyhow that teenagers have extremely delicate skin, it's the opposite really, quite resilient.
My only concern would be if she actually needs this product or that she's just been swayed by TikTok or similar, it's mostly a hydration boost, not something most teenagers struggle with. It can also help with soothing inflammation and healing so if she's consistently dealing with the aftermath of breakouts and angry skin I can see use for it in a teenager.