You have to mention the zip code of the Country that you have completed your 10th from. But not all countries have 6 digit zip codes and so if the Country that you completed your 10th from has only 5 digits, mention a "0" before the zip code. For example, if your zip code is 67895, enter it as 067895. That will be fine. And do not worry about not being qualified because according to the Information Brochure available at: https://jeemain.nta.nic.in/webinfo2021/File/GetFile?FileId=1&LangId=P, "

"Any Public School/ Board/ University examination in India or any foreign country recognized as equivalent to the 10+2 system by the Association of Indian Universities (AIU). So just enter the zip code as mentioned and you will be fine.