@koryei ! You could try applying with other proof of student status, such as a current student ID, class schedule or enrolment letter. Here's GitHub's official guide:
https://docs.github.com/en/education/about-github-education/github-education-for-students/apply-to-github-education-as-a-student

If GitHub requires a verified school email, I'd contact GitHub Education Support and explain the firewall issue. Hope that helps!

You can try applying with your personal email and submitting alternative proof of student status, such as a current student ID or enrollment certificate.

Go to https://github.com/settings/education/benefits and check whether GitHub offers an alternative verification method for your account. If the application specifically requires a school-issued email, contact GitHub Education Support at https://support.github.com/contact and explain that your school's mail restrictions prevent you from receiving verification emails.

Don't use a fake school email or someone else's credentials. Ask your school administration whether they can provide an alternative verification document or temporarily allow GitHub verification emails.