A co-signer is required for some applications but not all – some are approved to proceed without one, and where that is the case the co-signer step does not appear. Where a co-signer is required, it keeps prices affordable for everyone. If you don't have someone who meets the criteria, ask your university's international office – many institutions offer sponsorship schemes that act as co-signers.
What if I don't have a co-signer?
documents — from thestudentguarantor.com/faqs