Akshay, even NIOS students are eligible for NEET 2020. The same age criteria and aggregate against your Category apply. Have a look at NEET 2020 Eligiblity:

• Indian Nationals, NRIs, PIOs, OCIs, and Foreign Nationals
• No upper age limit as of now. The Candidate should be at least 17 years by December 31st of 2020
• You should have completed your 10+2 with Physics, Chemistry and Biology as your Core Subjects.
• 50% Aggregate in Physics, Chemistry and Biology for General Category, 45% for PWD and 40% for OBC,SC,ST Candidates.
• NIOS and Private Candidates are also eligible

Use the link: https://ntaneet.nic.in/Ntaneet/Registration/NewReg.aspx for filling the application form and you can check the complete application process at our page, https://medicine.careers360.com/articles/neet-application-form.