If am not wrong you are talking about Jharkhand State Open School(JSOS), If you are talking the same then no need to worry. It is recognised under the government of Jharkhand and the degree is accepted by the MHRD, Government of India. It is aimed to provide distance learning to those who cannot attend school.

You will need to submit your certificate of educational qualification for UPSC Mains which should be awarded by the university or an equivalent qualification as recognised by the UPSC. And since JSOS claims that MHRD accepts their certificate for any exam under government section. So I think you are eligible for it, there won't be any issues. And for more information you can visit JSOS official site.

Hope this may help you.