I spent an afternoon trying to track that down and honestly, it was a whole thing. The simplest route is definitely the library—they'll have the ebook through apps like Libby or Overdrive, and you can borrow it for free. It might have a waitlist, though, depending on your location.
If you're set on reading right now, the legal digital purchase from retailers like Amazon, Apple Books, or Kobo is the way to go. You'll own the file and can read it on any device. I remember when I wanted it, I ended up just buying it because I didn't want to wait for my library hold to come through. The convenience is worth the price for me, especially since I know I'll re-read it.
I'd steer clear of anything labeled 'VK online'—that usually points to unofficial uploads on that Russian social media platform, which aren't legal. Sarah J. Maas's publisher is pretty vigilant about taking those down, so even if you found a link, it'd likely be dead or full of pop-ups. Better to support the author and get a clean, complete copy.