Hi adib! So admirable you're wanting to join as a high school student! ^ ㅡ^ Kudos for you for being so proactive!
Unfortunately, the game jam is only open to students currently enrolled in a degree seeking program (undergrad/grad). Another high school student had asked about eligibility for joining on the Discord, and this is what Julia had said in response:
if you’re not in university you can still attend the workshops! just sign up with your school email ... the workshops are all a lecture format with Q&A time at the end
I believe you can still join the game jam itself, but you wouldn't be eligible for prizing! So there's nothing stopping you from coming into the community, mingling, and submitting something that the community can enjoy playing through. :D