How can I finance an iPhone 15 on a budget as an international student?

I want to buy an iphone 15 on finance but if I go to my carrier, they are asking me to get on line or get a post paid sim to get financing options but I am an international student and cannot afford to pay more than $70 a month for network and iphone. When I go to the apple store online and try to finance the phone using Apple Card, it asks me for the carrier information but when I put in the information it displays "The information you provided does not match the carrier's records. Please re-enter your information and try again, or contact T-Mobile". What should I do now?

[Re-Titled by Moderator]