Just finished, what a box! Here’s a few tips that can help.
Foothold: Check how you can escalate your privileges as a user on the academy, you’ll be led to a nice hidden place. Follow what you find, and you’ll find some interesting secrets. Use the secrets to your advantage to craft a gateway - what you want is closer than you think!
User: The academy has more secrets, just need to find them. You’ll find a few, but this particular secret is distinct from the others - don’t doubt yourself, try it!
Root: You’re considered a particular type of user, rather privileged, you can see what others have done. You might need to audit a thing or two, you’ll find a new secret. Afterwards you’ll discover a new privilege - just feed it what it wants and you’ll get root.