Going through the information brochure, I found your answer. I am quoting it exactly,
Nativity:-

Candidates of Tamil Nadu Nativity only will be considered for admission. However, candidates who have studied all 10th, 11th, 12th Standards in Tamil Nadu will be considered for admission, on producing proof of having studied 10th, 11th, 12th Standards in Schools located at Tamil Nadu. The candidates who have not studied all 10th, 11th, 12th standards in Tamil Nadu should produce the Certificate of Permanent Residence in Tamil Nadu in the prescribed proforma (Appendix VII) issued by the competent authorities. Candidates possessing community certificate issued by Government of Tamil Nadu need not submit Appendix VII.

Link: http://www.tnau.ac.in/admission/2019/UG_Admission_Brochure_2019.pdf